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6 | <title>Introduction to Moose</title> |
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36 | |
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40 | <div id="header"></div> |
41 | <div id="footer"> |
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44 | <br /><span xmlns:dc="http://purl.org/dc/elements/1.1/" href="http://purl.org/dc/dcmitype/Text" property="dc:title" rel="dc:type">Introduction to Moose</span> by <span xmlns:cc="http://creativecommons.org/ns#" property="cc:attributionName">David Rolsky</span> is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/us/">Creative Commons Attribution-Share Alike 3.0 United States License</a>. |
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45 | </div> |
46 | |
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47 | <h2>Introduction to Moose</h2> |
48 | </div> |
49 | </div> |
50 | |
51 | <div class="presentation"> |
52 | |
53 | <div class="slide"> |
54 | <h1>Introduction to Moose</h1> |
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55 | <h2><a href="git://git.moose.perl.org/moose-presentations.git"><tt>git://git.moose.perl.org/moose-presentations.git</tt></a></h2> |
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56 | </div> |
57 | |
58 | <div class="slide"> |
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59 | <h1>Introduce Yourselves</h1> |
60 | |
61 | <ul> |
62 | <li>Your name</li> |
63 | <li>What you do with Perl</li> |
64 | <li>Why you're here today (optional)</li> |
65 | </ul> |
66 | </div> |
67 | |
68 | <div class="slide"> |
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69 | <h1>Moose Summed Up</h1> |
70 | |
71 | <ul> |
72 | <li><strong>Declarative</strong> OO sugar</li> |
73 | <li>Introspectable</li> |
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74 | <li>Extensible (MooseX::* on CPAN)</li> |
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75 | </ul> |
76 | </div> |
77 | |
78 | <div class="slide"> |
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79 | <h1>Moose Background</h1> |
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80 | |
81 | <ul> |
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82 | <li>Created by Stevan Little, first released in 2006</li> |
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83 | <li>Moose builds on Perl 5's native OO</li> |
84 | <li>Borrows ideas from other languages, notably Perl 6</li> |
85 | <li>Provides semantics for common operations</li> |
86 | </ul> |
87 | </div> |
88 | |
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89 | <div class="slide fake-slide0"> |
90 | <h1>Part 0: Moose Concepts</h1> |
91 | </div> |
92 | |
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93 | <div class="slide"> |
94 | <h1>Classes</h1> |
95 | |
96 | <ul> |
97 | <li> |
98 | Classes have ... |
99 | <ul> |
100 | <li>Attributes</li> |
101 | <li>Methods</li> |
102 | <li>Superclasses</li> |
103 | <li>Method modifiers</li> |
104 | <li>Constructor and destructor</li> |
105 | <li>One metaclass object</li> |
106 | </ul> |
107 | </li> |
108 | <li>Classes do roles</li> |
109 | </ul> |
110 | </div> |
111 | |
112 | <div class="slide"> |
113 | <h1>Class Example</h1> |
114 | |
115 | <pre><code>package Person; |
116 | <span class="highlight">use Moose;</span></code></pre> |
117 | |
118 | <ul> |
119 | <li>Poof, a Moose-based class!</li> |
120 | </ul> |
121 | </div> |
122 | |
123 | <div class="slide"> |
124 | <h1>Attributes</h1> |
125 | |
126 | <ul> |
127 | <li>Aka property, slot, field, member variable</li> |
128 | <li>A piece of data owned by an object</li> |
129 | </ul> |
130 | </div> |
131 | |
132 | <div class="slide"> |
133 | <h1>Attributes</h1> |
134 | |
135 | <ul> |
136 | <li> |
137 | Attributes have ... |
138 | <ul> |
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139 | <li>Mutability (read-only vs read-write)</li> |
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140 | <li>An optional type</li> |
141 | <li>Accessor methods</li> |
142 | <li>Delegation methods</li> |
143 | <li>Optional default value</li> |
144 | <li>Many more features</li> |
145 | </ul> |
146 | </li> |
147 | <li>Stored in the object, but don't worry about that</li> |
148 | </ul> |
149 | </div> |
150 | |
151 | <div class="slide"> |
152 | <h1>Attribute Example</h1> |
153 | |
154 | <pre><code>package Person; |
155 | use Moose; |
156 | |
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157 | <span class="highlight">has first_name => ( is => 'rw' );</span></code></pre> |
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158 | |
159 | </div> |
160 | |
161 | <div class="slide"> |
162 | <h1>Methods</h1> |
163 | |
164 | <ul> |
165 | <li>Nothing fancy here, just Perl subroutines</li> |
166 | </ul> |
167 | |
168 | <pre><code>package Person; |
169 | use Moose; |
170 | |
171 | <span class="highlight">sub greet { ... }</span></code></pre> |
172 | </div> |
173 | |
174 | <div class="slide"> |
175 | <h1>Roles</h1> |
176 | |
177 | <ul> |
178 | <li>Classes <strong>do</strong> (or consume) roles</li> |
179 | <li>Similar to mixins and Java interfaces</li> |
180 | </ul> |
181 | </div> |
182 | |
183 | <div class="slide"> |
184 | <h1>Roles</h1> |
185 | |
186 | <ul> |
187 | <li>Like classes, can have attributes, methods, do roles</li> |
188 | <li>Roles can require methods</li> |
189 | <li>Roles are composed (flattened) into classes</li> |
190 | </ul> |
191 | </div> |
192 | |
193 | <div class="slide"> |
194 | <h1>Role Example</h1> |
195 | |
196 | <pre><code>package HasPermissions; |
197 | <span class="highlight">use Moose::Role;</span> |
198 | |
199 | has is_admin => ( is => 'rw' );</code></pre> |
200 | </div> |
201 | |
202 | <div class="slide"> |
203 | <h1>Role Example</h1> |
204 | |
205 | <p> |
206 | And then ... |
207 | </p> |
208 | |
209 | <pre><code>package Person; |
210 | use Moose; |
211 | |
212 | <span class="highlight">with 'HasPermissions';</span></code></pre> |
213 | </div> |
214 | |
215 | <div class="slide"> |
216 | <h1>Method Modifiers</h1> |
217 | |
218 | <ul> |
219 | <li>AKA advice</li> |
220 | <li>"<strong>Before</strong> foo(), do this first"</li> |
221 | <li>"Do this <strong>after</strong> foo()</li> |
222 | <li>"Put this code <strong>around</strong> foo()"</li> |
223 | </ul> |
224 | </div> |
225 | |
226 | <div class="slide"> |
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227 | <h1>Before and After</h1> |
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228 | |
229 | <pre><code>before 'foo' |
230 | => sub { warn 'About to call foo()' }; |
231 | |
232 | after 'foo' |
233 | => sub { warn 'Leaving foo()' };</code></pre> |
234 | |
235 | </div> |
236 | |
237 | <div class="slide"> |
238 | <h1>Around</h1> |
239 | |
240 | <pre><code>around 'foo' => sub { |
241 | my $real_foo = shift; |
242 | my $self = shift; |
243 | |
244 | warn 'Just before foo()'; |
245 | my @return = |
246 | $self->$real_foo( @_, bar => 42 ); |
247 | |
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248 | return ( |
249 | @return, |
250 | 'modify return values' |
251 | ); |
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252 | };</code></pre> |
253 | </div> |
254 | |
255 | <div class="slide"> |
256 | <h1>Type Constraints</h1> |
257 | |
258 | <ul> |
259 | <li>NOT A FULL-BLOWN TYPE SYSTEM!</li> |
260 | <li>But still darn useful</li> |
261 | <li>Constrain attribute values</li> |
262 | <li>Coerce from other types</li> |
263 | </ul> |
264 | </div> |
265 | |
266 | <div class="slide"> |
267 | <h1>Type Constraint Example</h1> |
268 | |
269 | <pre><code>package Person; |
270 | use Moose; |
271 | |
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272 | has weight => ( |
273 | is => 'ro', |
274 | <span class="highlight">isa => 'Int'</span>, |
275 | ); |
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276 | |
277 | # kaboom |
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278 | Person->new( weight => 'heavy' );</code></pre> |
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279 | </div> |
280 | |
281 | <div class="slide"> |
282 | <h1>Delegation</h1> |
283 | |
284 | <ul> |
285 | <li>Attributes can define delegations</li> |
286 | <li>Lets you hide some implementation details</li> |
287 | <li>Fewer objects to chase around</li> |
288 | </ul> |
289 | </div> |
290 | |
291 | <div class="slide"> |
292 | <h1>Delegation</h1> |
293 | |
294 | <pre><code>package Person; |
295 | use Moose; |
296 | |
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297 | has blog_uri => ( |
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298 | is => 'rw', |
299 | isa => 'URI', |
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300 | <span class="highlight">handles => { 'blog_host' => 'host' },</span> |
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301 | ); |
302 | |
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303 | <span class="highlight">$person->blog_host;</span> |
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304 | # really calls $person->blog_uri->host</code></pre> |
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305 | </div> |
306 | |
307 | <div class="slide"> |
308 | <h1>Constructors</h1> |
309 | |
310 | <ul> |
311 | <li>Moose creates <code>new()</code> for you</li> |
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312 | <li>Provide an optional <code>BUILDARGS()</code> and <code>BUILD()</code></li> |
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313 | </ul> |
314 | </div> |
315 | |
316 | <div class="slide"> |
317 | <h1>Destructors</h1> |
318 | |
319 | <ul> |
320 | <li>Provide an optional <code>DEMOLISH()</code></li> |
321 | </ul> |
322 | </div> |
323 | |
324 | <div class="slide"> |
325 | <h1>Moose Meta-API</h1> |
326 | |
327 | <ul> |
328 | <li>Answers questions like ... |
329 | <ul> |
330 | <li>What methods does this class have?</li> |
331 | <li>What are its parents?</li> |
332 | <li>What attributes does it have (including inherited attributes)?</li> |
333 | <li>What roles does it do?</li> |
334 | <li>Much, much, more</li> |
335 | </ul> |
336 | </li> |
337 | </ul> |
338 | </div> |
339 | |
340 | <div class="slide"> |
341 | <h1>Moose Meta-API</h1> |
342 | |
343 | <ul> |
344 | <li>Not just for introspection ... |
345 | <ul> |
346 | <li>Add methods, attributes, roles, etc</li> |
347 | <li>Extend and alter core features</li> |
348 | </ul> |
349 | </li> |
350 | </ul> |
351 | </div> |
352 | |
353 | <div class="slide"> |
354 | <h1>Why Moose?</h1> |
355 | |
356 | <ul> |
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357 | <li>A quick bit of propaganda ...</li> |
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358 | </ul> |
359 | </div> |
360 | |
361 | <div class="slide"> |
362 | <h1>With Moose</h1> |
363 | |
364 | <pre><code>package Person; |
365 | use Moose; |
366 | |
367 | has last_name => ( |
368 | is => 'rw', |
369 | isa => 'Str', |
370 | );</code></pre> |
371 | </div> |
372 | |
373 | <div class="slide"> |
374 | <h1>Without Moose</h1> |
375 | |
376 | <pre class="small"><code>package Person; |
377 | use strict; |
378 | use warnings; |
379 | use Carp 'confess'; |
380 | |
381 | sub new { |
382 | my $class = shift; |
383 | my %args = @_; |
384 | my $self = {}; |
385 | |
386 | if (exists $args{last_name}) { |
387 | confess "Attribute (last_name) does not pass the type constraint because: " |
388 | . "Validation failed for 'Str' with value $args{last_name}" |
389 | if ref($args{last_name}); |
390 | $self->{last_nane} = $args{last_name}; |
391 | } |
392 | |
393 | return bless $self, $class; |
394 | } |
395 | |
396 | sub last_name { |
397 | my $self = shift; |
398 | |
399 | if (@_) { |
400 | my $value = shift; |
401 | confess "Attribute (last_name) does not pass the type constraint because: " |
402 | . "Validation failed for 'Str' with value $value" |
403 | if ref($value); |
404 | $self->{last_name} = $value; |
405 | } |
406 | |
407 | return $self->{last_name}; |
408 | }</code></pre> |
409 | |
410 | </div> |
411 | |
412 | <div class="slide"> |
413 | <h1>Side by side</h1> |
414 | |
415 | <table class="side-by-side"> |
416 | <tr> |
417 | <td> |
418 | <pre><code>package Person; |
419 | use Moose; |
420 | |
421 | has last_name => ( |
422 | is => 'rw', |
423 | isa => 'Str', |
424 | );</code></pre> |
425 | </td> |
426 | <td> |
427 | <pre class="small"><code>package Person; |
428 | use strict; |
429 | use warnings; |
430 | use Carp 'confess'; |
431 | |
432 | sub new { |
433 | my $class = shift; |
434 | my %args = @_; |
435 | my $self = {}; |
436 | |
437 | if (exists $args{last_name}) { |
438 | confess "Attribute (last_name) does not pass the type constraint because: " |
439 | . "Validation failed for 'Str' with value $args{last_name}" |
440 | if ref($args{last_name}); |
441 | $self->{last_nane} = $args{last_name}; |
442 | } |
443 | |
444 | return bless $self, $class; |
445 | } |
446 | |
447 | sub last_name { |
448 | my $self = shift; |
449 | |
450 | if (@_) { |
451 | my $value = shift; |
452 | confess "Attribute (last_name) does not pass the type constraint because: " |
453 | . "Validation failed for 'Str' with value $value" |
454 | if ref($value); |
455 | $self->{last_name} = $value; |
456 | } |
457 | |
458 | return $self->{last_name}; |
459 | }</code></pre> |
460 | </td> |
461 | </tr> |
462 | </table> |
463 | |
464 | </div> |
465 | |
466 | <div class="slide"> |
467 | <h1>Side by side</h1> |
468 | |
469 | <table class="side-by-side"> |
470 | <tr> |
471 | <td> |
472 | <pre><code><span class="match-moose">package Person;</span> |
473 | use Moose; |
474 | |
475 | has last_name => ( |
476 | is => 'rw', |
477 | isa => 'Str', |
478 | );</code></pre> |
479 | </td> |
480 | <td> |
481 | <pre class="small"><code><span class="match-unsweet">package Person;</span> |
482 | use strict; |
483 | use warnings; |
484 | use Carp 'confess'; |
485 | |
486 | sub new { |
487 | my $class = shift; |
488 | my %args = @_; |
489 | my $self = {}; |
490 | |
491 | if (exists $args{last_name}) { |
492 | confess "Attribute (last_name) does not pass the type constraint because: " |
493 | . "Validation failed for 'Str' with value $args{last_name}" |
494 | if ref($args{last_name}); |
495 | $self->{last_nane} = $args{last_name}; |
496 | } |
497 | |
498 | return bless $self, $class; |
499 | } |
500 | |
501 | sub last_name { |
502 | my $self = shift; |
503 | |
504 | if (@_) { |
505 | my $value = shift; |
506 | confess "Attribute (last_name) does not pass the type constraint because: " |
507 | . "Validation failed for 'Str' with value $value" |
508 | if ref($value); |
509 | $self->{last_name} = $value; |
510 | } |
511 | |
512 | return $self->{last_name}; |
513 | }</code></pre> |
514 | </td> |
515 | </tr> |
516 | </table> |
517 | </div> |
518 | |
519 | <div class="slide"> |
520 | <h1>Side by side</h1> |
521 | |
522 | <table class="side-by-side"> |
523 | <tr> |
524 | <td> |
525 | <pre><code>package Person; |
526 | <span class="match-moose">use Moose;</span> |
527 | |
528 | has last_name => ( |
529 | is => 'rw', |
530 | isa => 'Str', |
531 | );</code></pre> |
532 | </td> |
533 | <td> |
534 | <pre class="small"><code>package Person; |
535 | <span class="match-unsweet">use strict; |
536 | use warnings; |
537 | use Carp 'confess'; |
538 | |
539 | sub new { |
540 | my $class = shift; |
541 | my %args = @_; |
542 | my $self = {};</span> |
543 | |
544 | if (exists $args{last_name}) { |
545 | confess "Attribute (last_name) does not pass the type constraint because: " |
546 | . "Validation failed for 'Str' with value $args{last_name}" |
547 | if ref($args{last_name}); |
548 | $self->{last_nane} = $args{last_name}; |
549 | } |
550 | |
551 | <span class="match-unsweet">return bless $self, $class; |
552 | }</span> |
553 | |
554 | sub last_name { |
555 | my $self = shift; |
556 | |
557 | if (@_) { |
558 | my $value = shift; |
559 | confess "Attribute (last_name) does not pass the type constraint because: " |
560 | . "Validation failed for 'Str' with value $value" |
561 | if ref($value); |
562 | $self->{last_name} = $value; |
563 | } |
564 | |
565 | return $self->{last_name}; |
566 | }</code></pre> |
567 | </td> |
568 | </tr> |
569 | </table> |
570 | </div> |
571 | |
572 | <div class="slide"> |
573 | <h1>Side by side</h1> |
574 | |
575 | <table class="side-by-side"> |
576 | <tr> |
577 | <td> |
578 | <pre><code>package Person; |
579 | use Moose; |
580 | |
581 | <span class="match-moose">has last_name => (</span> |
582 | is => 'rw', |
583 | isa => 'Str', |
584 | <span class="match-moose">);</span></code></pre> |
585 | </td> |
586 | <td> |
587 | <pre class="small"><code>package Person; |
588 | use strict; |
589 | use warnings; |
590 | use Carp 'confess'; |
591 | |
592 | sub new { |
593 | my $class = shift; |
594 | my %args = @_; |
595 | my $self = {}; |
596 | |
597 | <span class="match-unsweet">if (exists $args{last_name}) {</span> |
598 | confess "Attribute (last_name) does not pass the type constraint because: " |
599 | . "Validation failed for 'Str' with value $args{last_name}" |
600 | if ref($args{last_name}); |
601 | <span class="match-unsweet">$self->{last_nane} = $args{last_name}; |
602 | }</span> |
603 | |
604 | return bless $self, $class; |
605 | } |
606 | |
607 | sub last_name { |
608 | my $self = shift; |
609 | |
610 | if (@_) { |
611 | my $value = shift; |
612 | confess "Attribute (last_name) does not pass the type constraint because: " |
613 | . "Validation failed for 'Str' with value $value" |
614 | if ref($value); |
615 | $self->{last_name} = $value; |
616 | } |
617 | |
618 | return $self->{last_name}; |
619 | }</code></pre> |
620 | </td> |
621 | </tr> |
622 | </table> |
623 | </div> |
624 | |
625 | <div class="slide"> |
626 | <h1>Side by side</h1> |
627 | |
628 | <table class="side-by-side"> |
629 | <tr> |
630 | <td> |
631 | <pre><code>package Person; |
632 | use Moose; |
633 | |
634 | has last_name => ( |
635 | <span class="match-moose">is => 'rw',</span> |
636 | isa => 'Str', |
637 | );</code></pre> |
638 | </td> |
639 | <td> |
640 | <pre class="small"><code>package Person; |
641 | use strict; |
642 | use warnings; |
643 | use Carp 'confess'; |
644 | |
645 | sub new { |
646 | my $class = shift; |
647 | my %args = @_; |
648 | my $self = {}; |
649 | |
650 | if (exists $args{last_name}) { |
651 | confess "Attribute (last_name) does not pass the type constraint because: " |
652 | . "Validation failed for 'Str' with value $args{last_name}" |
653 | if ref($args{last_name}); |
654 | $self->{last_nane} = $args{last_name}; |
655 | } |
656 | |
657 | return bless $self, $class; |
658 | } |
659 | |
660 | <span class="match-unsweet">sub last_name { |
661 | my $self = shift; |
662 | |
663 | if (@_) { |
664 | my $value = shift;</span> |
665 | confess "Attribute (last_name) does not pass the type constraint because: " |
666 | . "Validation failed for 'Str' with value $value" |
667 | if ref($value); |
668 | <span class="match-unsweet">$self->{last_name} = $value; |
669 | } |
670 | |
671 | return $self->{last_name}; |
672 | }</span></code></pre> |
673 | </td> |
674 | </tr> |
675 | </table> |
676 | </div> |
677 | |
678 | <div class="slide"> |
679 | <h1>Side by side</h1> |
680 | |
681 | <table class="side-by-side"> |
682 | <tr> |
683 | <td> |
684 | <pre><code>package Person; |
685 | use Moose; |
686 | |
687 | has last_name => ( |
688 | is => 'rw', |
689 | <span class="match-moose">isa => 'Str',</span> |
690 | );</code></pre> |
691 | </td> |
692 | <td> |
693 | <pre class="small"><code>package Person; |
694 | use strict; |
695 | use warnings; |
696 | use Carp 'confess'; |
697 | |
698 | sub new { |
699 | my $class = shift; |
700 | my %args = @_; |
701 | my $self = {}; |
702 | |
703 | if (exists $args{last_name}) { |
704 | <span class="match-unsweet">confess "Attribute (last_name) does not pass the type constraint because: " |
705 | . "Validation failed for 'Str' with value $args{last_name}" |
706 | if ref($args{last_name});</span> |
707 | $self->{last_nane} = $args{last_name}; |
708 | } |
709 | |
710 | return bless $self, $class; |
711 | } |
712 | |
713 | sub last_name { |
714 | my $self = shift; |
715 | |
716 | if (@_) { |
717 | my $value = shift; |
718 | <span class="match-unsweet">confess "Attribute (last_name) does not pass the type constraint because: " |
719 | . "Validation failed for 'Str' with value $value" |
720 | if ref($value);</span> |
721 | $self->{last_name} = $value; |
722 | } |
723 | |
724 | return $self->{last_name}; |
725 | }</code></pre> |
726 | </td> |
727 | </tr> |
728 | </table> |
729 | </div> |
730 | |
731 | <div class="slide"> |
732 | <h1>Side by side</h1> |
733 | |
734 | <table class="side-by-side"> |
735 | <tr class="incremental"> |
736 | <td>5 lines</td> |
737 | <td>21 lines</td> |
738 | </tr> |
739 | <tr class="incremental"> |
740 | <td>92 characters</td> |
741 | <td>741 characters</td> |
742 | </tr> |
743 | <tr> |
744 | <td> |
745 | <pre><code>package Person; |
746 | use Moose; |
747 | |
748 | has last_name => ( |
749 | is => 'rw', |
750 | isa => 'Str', |
751 | );</code></pre> |
752 | </td> |
753 | <td> |
754 | <pre class="small"><code>package Person; |
755 | use strict; |
756 | use warnings; |
757 | use Carp 'confess'; |
758 | |
759 | sub new { |
760 | my $class = shift; |
761 | my %args = @_; |
762 | my $self = {}; |
763 | |
764 | if (exists $args{last_name}) { |
765 | confess "Attribute (last_name) does not pass the type constraint because: " |
766 | . "Validation failed for 'Str' with value $args{last_name}" |
767 | if ref($args{last_name}); |
768 | $self->{last_nane} = $args{last_name}; |
769 | } |
770 | |
771 | return bless $self, $class; |
772 | } |
773 | |
774 | sub last_name { |
775 | my $self = shift; |
776 | |
777 | if (@_) { |
778 | my $value = shift; |
779 | confess "Attribute (last_name) does not pass the type constraint because: " |
780 | . "Validation failed for 'Str' with value $value" |
781 | if ref($value); |
782 | $self->{last_name} = $value; |
783 | } |
784 | |
785 | return $self->{last_name}; |
786 | }</code></pre> |
787 | </td> |
788 | </tr> |
789 | </table> |
790 | </div> |
791 | |
792 | <div class="slide"> |
793 | <h1>Typo?</h1> |
794 | |
795 | <pre class="small"><code>sub new { |
796 | my $class = shift; |
797 | my %args = @_; |
798 | my $self = {}; |
799 | |
800 | if (exists $args{last_name}) { |
801 | confess "Attribute (last_name) does not pass the type constraint because: " |
802 | . "Validation failed for 'Str' with value $args{last_name}" |
803 | if ref($args{last_name}); |
804 | $self->{last_nane} = $args{last_name}; |
805 | } |
806 | |
807 | return bless $self, $class; |
808 | }</code></pre> |
809 | </div> |
810 | |
811 | <div class="slide"> |
812 | <h1>Typo?</h1> |
813 | |
814 | <pre class="small"><code>if (exists $args{last_name}) { |
815 | confess "Attribute (last_name) does not pass the type constraint because: " |
816 | . "Validation failed for 'Str' with value $args{last_name}" |
817 | if ref($args{last_name}); |
818 | $self->{last_nane} = $args{last_name}; |
819 | }</code></pre> |
820 | </div> |
821 | |
822 | <div class="slide"> |
823 | <h1>Typo?</h1> |
824 | |
825 | <code>$self->{last_nane} = $args{last_name};</code> |
826 | </div> |
827 | |
828 | <div class="slide"> |
829 | <h1>Typo?</h1> |
8d1ce1d7 |
830 | <code>$self->{last_na<span class="wrong">n</span>e}</code> |
b751d33f |
831 | </div> |
832 | |
833 | <div class="slide"> |
834 | <h1>Why Moose?</h1> |
835 | |
836 | <pre><code>package Person; |
837 | use Moose; |
838 | |
839 | has last_name => ( |
840 | is => 'rw', |
841 | isa => 'Str', |
842 | );</code></pre> |
843 | </div> |
844 | |
9b0c7222 |
845 | <div class="slide"> |
846 | <h1>More Why Moose?</h1> |
847 | |
848 | <ul> |
849 | <li>Less code == fewer bugs</li> |
850 | <li>Moose is well-tested, test your own code, not Moose</li> |
851 | <li>Focus on <strong>what</strong>, not <strong>how</strong></li> |
852 | </ul> |
853 | </div> |
854 | |
b751d33f |
855 | <div class="slide fake-slide0"> |
ba1c9923 |
856 | <h1>Part 1: Moose Classes</h1> |
b751d33f |
857 | </div> |
858 | |
859 | <div class="slide"> |
860 | <h1>Moose Classes</h1> |
861 | |
862 | <ul> |
863 | <li>Moose classes are Perl packages which <code>use Moose</code></li> |
864 | </ul> |
865 | </div> |
866 | |
867 | <div class="slide"> |
868 | <h1>Moose.pm and Your Class</h1> |
869 | |
870 | <pre><code>package Person; |
871 | use Moose;</code></pre> |
872 | |
873 | <ul> |
874 | <li><code>Moose.pm</code> provides declarative sugar</li> |
9b195048 |
875 | <li>Turns on <code>strict</code> and <code>warnings</code></li> |
b751d33f |
876 | <li>Creates metaclasses for your class: <code>Person->meta</code></li> |
877 | <li>Moose classes automatically inherit from <code>Moose::Object</code></li> |
878 | </ul> |
879 | </div> |
880 | |
881 | <div class="slide"> |
882 | <h1>What <code>Moose::Object</code> Provides</h1> |
883 | |
884 | <ul> |
885 | <li>Constructor - <code>new()</code></li> |
886 | <li>Calls your <code>BUILDARGS()</code> and/or <code>BUILD()</code></li> |
887 | <li>Calls your <code>DEMOLISH</code> during object destruction</li> |
888 | </ul> |
889 | </div> |
890 | |
891 | <div class="slide"> |
d6c8786d |
892 | <h1>BUILDARGS</h1> |
893 | |
894 | <ul> |
86178e0f |
895 | <li>Takes <code>@_</code>, returns a hash reference of attribute name/value pairs</li> |
d6c8786d |
896 | <li>Accepts a hash or hashref; throws otherwise</li> |
897 | <li>Provide your own for other cases</li> |
898 | <li><strong>Always</strong> call <code>$class->SUPER::BUILDARGS(@_)</code> as a fallback!</li> |
899 | </ul> |
900 | </div> |
901 | |
902 | <div class="slide"> |
903 | <h1>BUILDARGS Example</h1> |
904 | |
905 | <pre><code>package Person; |
906 | use Moose; |
907 | |
908 | sub BUILDARGS { |
909 | my $class = shift; |
910 | |
5e2eb691 |
911 | if ( @_ == 1 && ! ref $_[0] ) { |
d6c8786d |
912 | <span class="highlight">return { ssn => $_[0] };</span> |
913 | } |
d6c8786d |
914 | <span class="highlight">return $class->SUPER::BUILDARGS(@_)</span>; |
915 | } |
916 | |
917 | <span class="highlight">Person->new('123-45-6789')</span></code></pre> |
918 | </div> |
919 | |
920 | <div class="slide"> |
921 | <h1>BUILD</h1> |
922 | |
923 | <ul> |
924 | <li>Called after object is created, before <code>new</code> returns</li> |
925 | <li>Chance to do more complex validation, set complex attributes</li> |
926 | <li>Called in reverse inheritance order, parents to children</li> |
927 | <li>Return value is ignored</li> |
928 | </ul> |
929 | </div> |
930 | |
931 | <div class="slide"> |
932 | <h1>BUILD Example</h1> |
933 | |
934 | <pre><code>package Person; |
935 | use Moose; |
936 | |
937 | sub BUILD { |
938 | my $self = shift; |
939 | |
940 | if ( $self->country_of_residence |
941 | eq 'USA' ) { |
942 | die 'All US residents' |
943 | . ' must have an SSN' |
944 | unless $self->has_ssn; |
945 | } |
946 | }</code></pre> |
947 | </div> |
948 | |
949 | <div class="slide"> |
7205c6ef |
950 | <h1>Object Construction a la Moose</h1> |
951 | |
952 | <pre><code>Person->new(@_)</code></pre> |
953 | |
86178e0f |
954 | <ol style="margin-top: 0"> |
7205c6ef |
955 | <li>Calls <code>Person->BUILDARGS(@_)</code> to turn <code>@_</code> into a hashref</li> |
956 | <li>Blesses a reference</li> |
957 | <li>Populates attributes based on the hashref from #1</li> |
958 | <li>Calls <code>$new_object->BUILDALL($constructor_args)</code> |
959 | <br />... which calls all <code>BUILD</code> methods</li> |
960 | <li>Returns the object</li> |
961 | </ol> |
962 | </div> |
963 | |
964 | <div class="slide"> |
17d7a564 |
965 | <h1>The Object is Opaque</h1> |
7205c6ef |
966 | |
967 | <ul> |
968 | <li>Technically it's a hash reference</li> |
969 | <li><span class="wrong">If you <em>ever</em> treat it as one <strong>you are doing it wrong!</strong></span></li> |
970 | </ul> |
971 | </div> |
972 | |
973 | <div class="slide"> |
d6c8786d |
974 | <h1>DEMOLISH</h1> |
975 | |
976 | <ul> |
977 | <li>Like <code>DESTROY</code>, but Moose makes sure all <code>DEMOLISH</code> methods in a hierarchy are called</li> |
978 | <li>Called in normal inheritance order, children to parents</li> |
979 | </ul> |
980 | </div> |
981 | |
982 | <div class="slide"> |
b751d33f |
983 | <h1>extends</h1> |
984 | |
985 | <ul> |
986 | <li><code>extends</code> is sugar for declaring parent classes</li> |
1847dd9e |
987 | <li>Also ensures metaclass compatibility between parent and child</li> |
988 | <li>Do not <code>use base</code></li> |
b751d33f |
989 | </ul> |
990 | |
991 | <pre><code>package Employee; |
992 | use Moose; |
993 | <span class="highlight">extends 'Person';</span></code></pre> |
994 | </div> |
995 | |
996 | <div class="slide"> |
997 | <h1>extends</h1> |
998 | |
999 | <ul> |
1000 | <li>Each call to <code>extends</code> <strong>resets</strong> your parents</li> |
1001 | </ul> |
1002 | |
5d572684 |
1003 | <h2 class="wrong">Wrong</h2> |
b751d33f |
1004 | |
9b195048 |
1005 | <pre><code>package EvilEmployee; |
b751d33f |
1006 | use Moose; |
1007 | extends 'Person'; |
55906a14 |
1008 | extends 'Thief';</code></pre> |
b751d33f |
1009 | |
5d572684 |
1010 | <h2 class="right">Right</h2> |
b751d33f |
1011 | |
9b195048 |
1012 | <pre><code>package EvilEmployee; |
b751d33f |
1013 | use Moose; |
55906a14 |
1014 | extends 'Person', 'Thief';</code></pre> |
b751d33f |
1015 | </div> |
1016 | |
1017 | <div class="slide"> |
1018 | <h1>Extending un-Moose-y Parents</h1> |
1019 | |
1020 | <pre><code>package My::LWP; |
1021 | use Moose; |
55906a14 |
1022 | extends 'LWP';</code></pre> |
b751d33f |
1023 | |
1024 | <ul> |
1025 | <li>No <code>Moose::Object</code>, so ... |
1026 | <ul> |
1027 | <li>No attribute-handling <code>new()</code></li> |
1028 | <li>No <code>BUILDARGS()</code> or <code>BUILD()</code></li> |
1029 | <li>No <code>DEMOLISH()</code></li> |
1030 | </ul> |
1031 | </li> |
1032 | <li>But see <code>MooseX::NonMoose</code> for a workaround</li> |
1033 | </ul> |
1034 | </div> |
1035 | |
1036 | <div class="slide"> |
9fa24ee2 |
1037 | <h1><code>override</code> and <code>super</code></h1> |
9b195048 |
1038 | |
1039 | <ul> |
9fa24ee2 |
1040 | <li><code>override</code> is another method modifier</li> |
9b195048 |
1041 | <li>An alternative to Perl's <code>SUPER::</code></li> |
1042 | </ul> |
1043 | </div> |
1044 | |
1045 | <div class="slide"> |
9fa24ee2 |
1046 | <h1><code>override</code> and <code>super</code></h1> |
9b195048 |
1047 | |
1048 | <pre><code>package Employee; |
1049 | use Moose; |
1050 | |
26164c8d |
1051 | <span class="current incremental">extends 'Person';</span> |
9b195048 |
1052 | |
9fa24ee2 |
1053 | <span class="incremental">override</span> work => sub { |
9b195048 |
1054 | my $self = shift; |
1055 | |
debc93f8 |
1056 | die "Pay me first" |
1057 | unless $self->got_paid; |
9b195048 |
1058 | <span class="incremental">super();</span> |
1059 | }<span class="incremental">;</span></code></pre> |
55906a14 |
1060 | </div> |
9b195048 |
1061 | |
1062 | <div class="slide"> |
1063 | <h1>Caveat <code>super</code></h1> |
1064 | |
1065 | <ul> |
1066 | <li>Mostly like <code>$self->SUPER::work(@_)</code></li> |
1067 | <li><strong>But</strong> cannot change <code>@_</code>!</li> |
1068 | <li>Binds the parent's method at compile time</li> |
16efce7a |
1069 | <li>Parent determined by checking <code>Child->meta()->superclasses()</code></li> |
9b195048 |
1070 | </ul> |
1071 | </div> |
1072 | |
1073 | <div class="slide"> |
e43c4c2a |
1074 | <h1>Minimal Attributes</h1> |
9b195048 |
1075 | |
1076 | <ul> |
1077 | <li><code>has 'foo'</code></li> |
1078 | <li>Use <code>is => 'ro'</code> or <code>is => 'rw'</code></li> |
1079 | <li>Attributes without "is" have no accessors</li> |
1080 | </ul> |
1081 | </div> |
1082 | |
1083 | <div class="slide"> |
1084 | <h1>Read-write attributes</h1> |
1085 | |
1086 | <pre><code>package Person; |
1087 | use Moose; |
1088 | |
55906a14 |
1089 | has first_name => ( <span class="highlight">is => 'rw'</span> ); |
9b195048 |
1090 | |
1091 | my $person = |
1092 | Person->new( first_name => 'Dave' ); |
1093 | |
1094 | $person->first_name('Stevan'); |
1095 | print $person->first_name; # Stevan</code></pre> |
1096 | |
1097 | </div> |
1098 | |
1099 | <div class="slide"> |
1100 | <h1>Read-only attributes</h1> |
1101 | |
1102 | <pre><code>package Person; |
1103 | use Moose; |
1104 | |
55906a14 |
1105 | has first_name => ( <span class="highlight">is => 'ro'</span> ); |
9b195048 |
1106 | |
1107 | my $person = |
1108 | Person->new( first_name => 'Dave' ); |
1109 | |
1110 | $person->first_name('Stevan'); |
1111 | print $person->first_name; # Dave</code></pre> |
1112 | |
1113 | </div> |
1114 | |
1115 | <div class="slide"> |
1116 | <h1>There is More to Come</h1> |
1117 | |
1118 | <ul> |
1119 | <li>Attributes have a <em>lot</em> of features</li> |
1120 | </ul> |
1121 | </div> |
1122 | |
1123 | <div class="slide"> |
b751d33f |
1124 | <h1>Cleaning Up Moose Droppings</h1> |
1125 | |
1126 | <pre><code>package Person; |
1127 | use Moose; |
1128 | |
1129 | # true |
1130 | Person->can('extends');</code></pre> |
1131 | |
1132 | <ul> |
1133 | <li>Not very hygienic</li> |
1134 | </ul> |
1135 | </div> |
1136 | |
1137 | <div class="slide"> |
1138 | <h1>Cleaning Up Moose Droppings</h1> |
1139 | |
1140 | <pre><code>package Person; |
1141 | use Moose; |
1142 | |
1143 | ... |
1144 | |
1145 | no Moose; |
1146 | |
1147 | # false |
1148 | Person->can('extends');</code></pre> |
1149 | </div> |
1150 | |
1151 | <div class="slide"> |
1152 | <h1>No Moose</h1> |
1153 | |
1154 | <ul> |
78c5b76a |
1155 | <li>Cleaning up is a best practice</li> |
1156 | <li>Say <code>no Moose</code> at the end of a package</li> |
debc93f8 |
1157 | <li>Or <code>use namespace::autoclean</code> at the top</li> |
b751d33f |
1158 | <li>Just do it</li> |
1159 | </ul> |
1160 | </div> |
1161 | |
1162 | <div class="slide"> |
1163 | <h1>Immutability</h1> |
1164 | |
1165 | <ul> |
1166 | <li><span style="font-family: URW Chancery L; font-size: 140%">Stevan's Incantation of Fleet-Footedness</span></li> |
1167 | </ul> |
1168 | |
1169 | <pre><code>package Person; |
1170 | use Moose; |
1171 | |
1172 | <span class="highlight">__PACKAGE__->meta->make_immutable;</span></code></pre> |
1173 | </div> |
1174 | |
9b195048 |
1175 | <div class="slide"> |
1176 | <h1>What <code>make_immutable</code> does</h1> |
1177 | |
1178 | <ul> |
1179 | <li>Magic</li> |
1180 | <li>Uses <code>eval</code> to "inline" a constructor</li> |
1181 | <li>Memoizes a lot of meta-information</li> |
1182 | <li>Makes loading your class slower</li> |
1183 | <li>Makes object creation <em>much</em> faster</li> |
1184 | </ul> |
1185 | </div> |
1186 | |
1187 | <div class="slide"> |
1188 | <h1>When to Immutabilize?</h1> |
1189 | |
1190 | <ul> |
1191 | <li><em>Almost</em> always</li> |
1192 | <li>Startup time vs execution time</li> |
1193 | </ul> |
1194 | </div> |
1195 | |
ddd87d75 |
1196 | <div class="slide"> |
55906a14 |
1197 | <h1>Classes Summary</h1> |
1198 | |
1199 | <ul> |
1200 | <li><code>use Moose</code></li> |
1201 | <li><code>Class->meta</code></li> |
1202 | <li><code>Moose::Object</code> base class</li> |
9fa24ee2 |
1203 | <li><code>extends</code>, <code>override</code>, and <code>super</code></li> |
55906a14 |
1204 | <li>Simple attributes: <code>has</code>, <code>is => 'ro'</code>, & <code>is => 'rw'</code></li> |
1205 | <li><code>no Moose</code></li> |
1206 | <li><code>__PACKAGE__->meta->make_immutable</code></li> |
1207 | </ul> |
1208 | </div> |
1209 | |
1210 | <div class="slide"> |
26164c8d |
1211 | <h1>Questions?</h1> |
1212 | </div> |
1213 | |
1214 | <div class="slide"> |
ba1c9923 |
1215 | <h1>Exercises</h1> |
ddd87d75 |
1216 | |
8d1ce1d7 |
1217 | <pre># cd exercises |
bcbafd14 |
1218 | |
4a2daaa5 |
1219 | # perl bin/prove -lv t/00-prereq.t |
ddd87d75 |
1220 | |
bcbafd14 |
1221 | # perl install-moose (if needed) |
ddd87d75 |
1222 | |
ba1c9923 |
1223 | # perl bin/prove -lv t/01-classes.t |
1224 | |
ff112bdd |
1225 | # edit lib/Person.pm and lib/Employee.pm |
1226 | |
55906a14 |
1227 | Iterate til this passes all its tests</pre> |
1228 | </div> |
1229 | |
1230 | <div class="slide fake-slide0"> |
1231 | <h1>Part 2: Roles</h1> |
1232 | </div> |
1233 | |
1234 | <div class="slide"> |
1235 | <h1>Just What Is a Role?</h1> |
1236 | |
1237 | <ul> |
1238 | <li>Mixin? Interface? Trait?</li> |
1239 | <li>Yes ... and more!</li> |
1240 | </ul> |
1241 | </div> |
1242 | |
1243 | <div class="slide"> |
debc93f8 |
1244 | <h1>Roles - State <strong>and</strong> Behavior</h1> |
55906a14 |
1245 | |
1246 | <pre><code>package HasPermissions; |
1247 | use Moose::Role; |
26164c8d |
1248 | <span class="current incremental"># state |
55906a14 |
1249 | has access_level => ( is => 'rw' );</span> |
1250 | |
1251 | <span class="incremental"># behavior |
1252 | sub can_access { |
1253 | my $self = shift; |
1254 | my $required = shift; |
1255 | |
debc93f8 |
1256 | return $self->access_level |
1257 | >= $required; |
55906a14 |
1258 | }</span></code></pre> |
1259 | |
1260 | </div> |
1261 | |
1262 | <div class="slide"> |
1263 | <h1>Roles Can Define Interfaces</h1> |
1264 | |
1265 | <pre><code>package Printable; |
1266 | use Moose::Role; |
1267 | |
1268 | requires 'as_string';</code></pre> |
1269 | </div> |
1270 | |
1271 | <div class="slide"> |
1272 | <h1>Roles Can Do All Three</h1> |
1273 | |
1274 | <pre><code>package Printable; |
1275 | use Moose::Role; |
1276 | |
1277 | requires 'as_string'; |
1278 | |
1279 | has has_been_printed => ( is => 'rw' ); |
1280 | |
1281 | sub print { |
1282 | my $self = shift; |
1283 | print $self->as_string; |
1284 | $self->has_been_printed(1); |
1285 | }</code></pre> |
1286 | </div> |
1287 | |
1288 | <div class="slide"> |
1289 | <h1>Classes Consume Roles</h1> |
1290 | |
1291 | <pre><code>package Person; |
1292 | use Moose; |
1293 | |
1294 | with 'HasPermissions';</code></pre> |
1295 | </div> |
1296 | |
1297 | <div class="slide"> |
1298 | <h1>Classes Consume Roles</h1> |
1299 | |
1300 | <pre><code>my $person = Person->new( |
debc93f8 |
1301 | first_name => 'Kenichi', |
1302 | last_name => 'Asai', |
55906a14 |
1303 | access_level => 42, |
1304 | ); |
1305 | |
1306 | print $person->full_name |
1307 | . ' has ' |
1308 | . $person->can_access(42) |
1309 | ? 'great power' |
1310 | : 'little power';</code></pre> |
1311 | </div> |
1312 | |
1313 | <div class="slide"> |
1314 | <h1>Roles in Practice</h1> |
1315 | |
1316 | <ul> |
1317 | <li>Consuming a role =~ inlining the role</li> |
1318 | </ul> |
1319 | </div> |
1320 | |
1321 | <div class="slide"> |
1322 | <h1>In Other Words ...</h1> |
1323 | |
1324 | <pre><code>package Person; |
1325 | use Moose; |
1326 | |
1327 | <span class="highlight">with 'Printable';</span></code></pre> |
1328 | </div> |
1329 | |
1330 | <div class="slide"> |
1331 | <h1>In Other Words ...</h1> |
1332 | |
1333 | <pre><code>package Person; |
1334 | use Moose; |
1335 | |
1336 | <span class="delete">with 'Printable';</span> |
1337 | |
1338 | <span class="highlight">has has_been_printed => ( is => 'rw' ); |
1339 | |
1340 | sub print { |
1341 | my $self = shift; |
1342 | print $self->as_string; |
1343 | $self->has_been_printed(1); |
1344 | }</span></code></pre> |
1345 | </div> |
1346 | |
1347 | <div class="slide"> |
1348 | <h1>Except</h1> |
1349 | |
1350 | <ul> |
1351 | <li>Role consumption is introspectable</li> |
1352 | </ul> |
1353 | |
1354 | <pre><code>if ( Person->does('Printable') ) { ... } |
1355 | |
1356 | # or ... |
1357 | |
debc93f8 |
1358 | Person->meta->does('Printable')</code></pre> |
55906a14 |
1359 | |
1360 | </div> |
1361 | |
1362 | <div class="slide"> |
1363 | <h1>These Names Are the Same</h1> |
1364 | |
1365 | <ul> |
1366 | <li>What if a role and class define the same method?</li> |
1367 | <li>A class's <em>local</em> methods win over the role's</li> |
1368 | <li>The role's methods win over the class's <em>inherited</em> methods</li> |
1369 | </ul> |
1370 | </div> |
1371 | |
1372 | <div class="slide"> |
1373 | <h1>Conflicts Between Roles</h1> |
1374 | |
1375 | <ul> |
1376 | <li>Two roles with a method of the same name</li> |
1377 | <li>Generates a compile-time error when consumed by a class</li> |
1378 | </ul> |
1379 | </div> |
1380 | |
1381 | <div class="slide"> |
1382 | <h1>Conflict Example</h1> |
1383 | |
1384 | <pre><code>package IsFragile; |
1385 | use Moose::Role; |
1386 | |
1387 | sub break { ... } |
1388 | |
1389 | package CanBreakdance; |
1390 | use Moose::Role; |
1391 | |
1392 | sub break { ... }</code></pre> |
1393 | </div> |
1394 | |
1395 | <div class="slide"> |
1396 | <h1>Conflict Example</h1> |
1397 | |
1398 | <pre><code>package FragileDancer; |
1399 | use Moose; |
1400 | |
1401 | <span class="highlight">with 'IsFragile', 'CanBreakdance';</span></code></pre> |
1402 | |
1403 | <ul> |
1404 | <li>Only one <code>with</code>!</li> |
1405 | </ul> |
1406 | </div> |
1407 | |
1408 | <div class="slide"> |
1409 | <h1>Conflict Resolution</h1> |
1410 | |
1411 | <ul> |
0412f089 |
1412 | <li>The consuming class must resolve the conflict by implementing the method</li> |
55906a14 |
1413 | <li>Can use some combination of method exclusion and aliasing</li> |
1414 | </ul> |
1415 | </div> |
1416 | |
1417 | <div class="slide"> |
1418 | <h1>Method Aliasing</h1> |
1419 | |
1420 | <pre><code>package FragileDancer; |
1421 | use Moose; |
1422 | |
1423 | <span class="highlight">with 'IsFragile' => |
debc93f8 |
1424 | { -alias => |
55906a14 |
1425 | { break => 'break_bone' } }, |
1426 | 'CanBreakdance' => |
debc93f8 |
1427 | { -alias => |
55906a14 |
1428 | { break => 'break_it_down' } };</span></code></pre> |
1429 | |
1430 | <ul> |
1431 | <li>Renames the roles' methods</li> |
1432 | <li>Still conflicts, need to <code>exclude</code> as well</li> |
1433 | </ul> |
1434 | </div> |
1435 | |
1436 | <div class="slide"> |
1437 | <h1>Method Exclusion</h1> |
1438 | |
1439 | <pre><code>package FragileDancer; |
1440 | use Moose; |
1441 | |
1442 | <span class="highlight">with 'IsFragile' => |
debc93f8 |
1443 | { -alias => |
55906a14 |
1444 | { break => 'break_bone' }, |
debc93f8 |
1445 | -excludes => 'break' }, |
55906a14 |
1446 | 'CanBreakdance' => |
debc93f8 |
1447 | { -alias => |
e326acd6 |
1448 | { break => 'break_it_down' }, |
debc93f8 |
1449 | -excludes => 'break' };</span></code></pre> |
55906a14 |
1450 | </div> |
1451 | |
1452 | <div class="slide"> |
1453 | <h1>And then ...</h1> |
1454 | |
1455 | <pre><code>package FragileDancer; |
1456 | use Moose; |
ddd87d75 |
1457 | |
55906a14 |
1458 | sub break { |
1459 | my $self = shift; |
1460 | |
e326acd6 |
1461 | $self->break_it_down; |
232c184d |
1462 | if ( rand(1) < 0.5 ) { |
55906a14 |
1463 | $self->break_bone; |
1464 | } |
1465 | }</code></pre> |
1466 | </div> |
1467 | |
1468 | <div class="slide"> |
1469 | <h1>Still Full of Fail</h1> |
1470 | |
1471 | <ul> |
1472 | <li>Roles are also about semantics!</li> |
1473 | <li>We've fulfilled the letter and lost the spirit</li> |
1474 | <li>Roles have a <em>meaning</em></li> |
1475 | <li>Think twice before blindly aliasing and excluding methods!</li> |
1476 | </ul> |
1477 | </div> |
1478 | |
1479 | <div class="slide"> |
1480 | <h1>Hot Role-on-Role Action</h1> |
1481 | |
1482 | <pre><code>package Comparable; |
1483 | use Moose::Role; |
1484 | |
1485 | requires 'compare';</code></pre> |
1486 | </div> |
1487 | |
1488 | <div class="slide"> |
1489 | <h1>Hot Role-on-Role Action</h1> |
1490 | |
1491 | <pre><code>package TestsEquality; |
1492 | use Moose::Role; |
1493 | |
1494 | with 'Comparable'; |
1495 | |
1496 | sub is_equal { |
1497 | my $self = shift; |
1498 | return $self->compare(@_) == 0; |
1499 | }</code></pre> |
1500 | </div> |
1501 | |
1502 | <div class="slide"> |
1503 | <h1>And then ...</h1> |
1504 | |
1505 | <pre><code>package Integer; |
1506 | use Moose; |
1507 | |
1508 | with 'TestsEquality'; |
1509 | |
1510 | # Satisfies the Comparable role |
1511 | sub compare { ... } |
1512 | |
1513 | Integer->does('TestsEquality'); # true |
1514 | Integer->does('Comparable'); # also true!</code></pre> |
1515 | </div> |
1516 | |
1517 | <div class="slide"> |
1518 | <h1>Name Conflicts Between Roles</h1> |
1519 | |
1520 | <pre><code>package HasSubProcess; |
1521 | use Moose::Role; |
1522 | |
1523 | <span class="highlight">sub execute { ... }</span> |
1524 | |
1525 | package Killer; |
1526 | use Moose::Role; |
1527 | |
1528 | with 'HasSubProcess'; |
1529 | |
1530 | <span class="highlight">sub execute { ... }</span></code></pre> |
1531 | </div> |
1532 | |
1533 | <div class="slide"> |
1534 | <h1>Delayed Conflict</h1> |
1535 | |
1536 | <pre><code>package StateOfTexas; |
1537 | with 'Killer';</code></pre> |
1538 | |
1539 | <ul> |
1540 | <li><code>StateOfTexas</code> must implement its own <code>execute</code></li> |
1541 | <li>But loading the <code>Killer</code> role by itself does not cause an error</li> |
1542 | </ul> |
1543 | </div> |
1544 | |
1545 | <div class="slide"> |
1546 | <h1>Roles as Interfaces</h1> |
1547 | |
1548 | <ul> |
1549 | <li>Roles can <code>require</code> methods of their consumers</li> |
1550 | <li>Compile-time checks</li> |
1551 | <li>Method must exist when the role is consumed</li> |
1552 | </ul> |
1553 | </div> |
1554 | |
1555 | <div class="slide"> |
1556 | <h1>The Attribute Gotcha</h1> |
1557 | |
1558 | <pre><code>package HasSize; |
1559 | use Moose::Role; |
1560 | |
26164c8d |
1561 | <span class="current incremental">requires 'size';</span> |
55906a14 |
1562 | |
1563 | package Shirt; |
1564 | use Moose; |
1565 | |
1566 | <span class="incremental">with 'HasSize'; |
1567 | |
1568 | has size => ( is => 'ro' );</span></code></pre> |
1569 | </div> |
1570 | |
1571 | <div class="slide"> |
1572 | <h1>The Attribute Gotcha Workaround</h1> |
1573 | |
1574 | <pre><code>package HasSize; |
1575 | use Moose::Role; |
1576 | |
1577 | requires 'size'; |
1578 | |
1579 | package Shirt; |
1580 | use Moose; |
1581 | |
1582 | has size => ( is => 'ro' ); |
1583 | |
1584 | with 'HasSize';</code></pre> |
1585 | </div> |
1586 | |
1587 | <div class="slide"> |
1588 | <h1>Compile-time Is a Lie</h1> |
1589 | |
1590 | <ul> |
1591 | <li>Really, it's <em>package load</em> time</li> |
1592 | <li>That's run-time, but before the "real" run-time</li> |
1593 | <li>Moose does not rewire Perl, it's just sugar!</li> |
1594 | <li>(but <code>MooseX::Declare</code> <em>does</em> rewire Perl)</li> |
1595 | </ul> |
1596 | </div> |
1597 | |
1598 | <div class="slide"> |
1599 | <h1>Enforcing Roles</h1> |
1600 | |
1601 | <pre><code>package Comparison; |
1602 | use Moose; |
1603 | |
1604 | has [ 'left', 'right' ] => ( |
1605 | is => 'ro', |
1606 | <span class="highlight">does => 'Comparable',</span> |
1607 | ); |
1608 | </code></pre> |
1609 | |
1610 | <ul> |
1611 | <li>A sneak peek at type constraints</li> |
1612 | </ul> |
1613 | </div> |
1614 | |
1615 | |
1616 | <div class="slide"> |
1617 | <h1>Roles Can Be Applied to Objects</h1> |
1618 | |
1619 | <pre><code>use Moose::Util qw( apply_all_roles ); |
1620 | |
1621 | my $fragile_person = Person->new( ... ); |
debc93f8 |
1622 | apply_all_roles( $fragile_person, |
1623 | 'IsFragile' );</code></pre> |
55906a14 |
1624 | |
1625 | <ul> |
1626 | <li>Does not change the <code>Person</code> class</li> |
1627 | <li>Works with non-Moose classes, great for monkey-patching!</li> |
1628 | </ul> |
1629 | </div> |
1630 | |
1631 | <div class="slide"> |
1632 | <h1>Roles Are Dirty Too</h1> |
1633 | |
1634 | <ul> |
1635 | <li>Once again, clean up those Moose droppings</li> |
1636 | </ul> |
1637 | |
1638 | <pre><code>package Comparable; |
1639 | use Moose::Role; |
1640 | |
1641 | requires 'compare'; |
1642 | |
1643 | <span class="highlight">no Moose::Role;</span></code></pre> |
1644 | |
1645 | <ul> |
1646 | <li>But roles cannot be made immutable</li> |
1647 | </ul> |
1648 | </div> |
1649 | |
1650 | <div class="slide"> |
1651 | <h1>The Zen of Roles</h1> |
1652 | |
1653 | <ul> |
1654 | <li>Roles represent discrete units of ... |
1655 | <ul> |
1656 | <li>state</li> |
1657 | <li>behavior</li> |
1658 | <li>interface</li> |
1659 | </ul> |
1660 | </li> |
1661 | <li>Roles are shareable between unrelated classes</li> |
1662 | <li>Roles are what a class <em>does</em>, not what it <em>is</em></li> |
1663 | <li>Roles <em>add</em> functionality, inheritance <em>specializes</em></li> |
1664 | </ul> |
1665 | </div> |
1666 | |
1667 | <div class="slide"> |
1668 | <h1>Abstract Examples</h1> |
1669 | |
1670 | <ul> |
1671 | <li>Human <em>@ISA</em> Animal</li> |
1672 | <li>Human <em>does</em> Toolmaker (as <em>does</em> Chimpanzee)</li> |
1673 | <li>Car <em>@ISA</em> Vehicle</li> |
1674 | <li>Car <em>does</em> HasEngine</li> |
1675 | </ul> |
1676 | </div> |
1677 | |
1678 | <div class="slide"> |
1679 | <h1>Real Examples</h1> |
1680 | |
1681 | <ul> |
1682 | <li>Objects representing SQL database components and queries |
1683 | <ul> |
1684 | <li>Schema, Table, Column, ColumnAlias</li> |
1685 | <li>Select, Insert, Update, Delete</li> |
1686 | </ul> |
1687 | </li> |
1688 | </ul> |
1689 | </div> |
1690 | |
1691 | <div class="slide"> |
1692 | <h1>Real Examples</h1> |
1693 | |
1694 | <ul> |
1695 | <li>Column and ColumnAlias both <em>do</em> ColumnLike</li> |
1696 | <li>ColumnLike things can be used in certain parts of queries</li> |
1697 | <li>All queries <em>do</em> HasWhereClause</li> |
1698 | <li>Select <em>does</em> Comparable and Selectable (for subselects)</li> |
1699 | <li>A where clause requires its components to <em>do</em> Comparable</li> |
1700 | </ul> |
1701 | </div> |
1702 | |
1703 | <div class="slide"> |
26164c8d |
1704 | <h1>Roles Summary</h1> |
1705 | |
1706 | <ul> |
1707 | <li>Roles can define an interface with <code>requires</code></li> |
1708 | <li>Roles can have state (attributes) and behavior (methods)</li> |
1709 | <li>Roles can mix interface, state, & behavior</li> |
1710 | <li>Roles are composed (flattened) into classes</li> |
1711 | <li>Roles can do other roles</li> |
1712 | <li>Roles can be used as a type in APIs (must do Comparable)</li> |
1713 | </ul> |
1714 | </div> |
1715 | |
1716 | <div class="slide"> |
1717 | <h1>Questions?</h1> |
1718 | </div> |
1719 | |
1720 | <div class="slide"> |
55906a14 |
1721 | <h1>Exercises</h1> |
1722 | |
8d1ce1d7 |
1723 | <pre># cd exercises |
55906a14 |
1724 | # perl bin/prove -lv t/02-roles.t |
1725 | |
1726 | Iterate til this passes all its tests</pre> |
1727 | </div> |
1728 | |
8d1ce1d7 |
1729 | <div class="slide fake-slide0"> |
1730 | <h1>Part 3: Basic Attributes</h1> |
1731 | </div> |
1732 | |
1733 | <div class="slide"> |
1734 | <h1>Attributes Are Huge</h1> |
1735 | |
1736 | <ul> |
1737 | <li>Moose's biggest feature</li> |
1738 | <li>The target of <em>many</em> MooseX modules</li> |
1739 | </ul> |
1740 | </div> |
1741 | |
1742 | <div class="slide"> |
1743 | <h1>Quick Review</h1> |
1744 | |
1745 | <ul> |
1746 | <li>Declared with <code>has</code></li> |
1747 | <li>Read-only or read-write</li> |
1748 | </ul> |
1749 | |
1750 | <pre><code>package Shirt; |
1751 | use Moose; |
1752 | |
1753 | has 'color' => ( is => 'ro' ); |
1754 | has 'is_ripped' => ( is => 'rw' );</code></pre> |
1755 | </div> |
1756 | |
1757 | <div class="slide"> |
1758 | <h1>Required-ness</h1> |
1759 | |
1760 | <ul> |
1761 | <li>Required means "must be passed to the constructor"</li> |
1762 | <li>But can be <code>undef</code></li> |
1763 | </ul> |
1764 | </div> |
1765 | |
1766 | <div class="slide"> |
1767 | <h1>Required-ness</h1> |
1768 | |
1769 | <pre><code>package Person; |
1770 | use Moose; |
1771 | |
1772 | has first_name => ( |
1773 | is => 'ro', |
26164c8d |
1774 | <span class="current incremental">required => 1,</span> |
8d1ce1d7 |
1775 | ); |
1776 | |
1777 | <span class="incremental">Person->new( first_name => undef ); # ok |
1778 | Person->new(); # kaboom</span></code></pre> |
1779 | </div> |
1780 | |
1781 | <div class="slide"> |
1782 | <h1>Default and Builder</h1> |
1783 | |
1784 | <ul> |
1785 | <li>Attributes can have defaults</li> |
7504f80b |
1786 | <li>Simple non-reference scalars (number, string)</li> |
8d1ce1d7 |
1787 | <li>Subroutine reference</li> |
1788 | <li>A builder method</li> |
1789 | </ul> |
1790 | </div> |
1791 | |
1792 | <div class="slide"> |
1793 | <h1>Default</h1> |
1794 | |
1795 | <ul> |
1796 | <li>Can be a non-reference scalar (including <code>undef</code>)</li> |
1797 | </ul> |
1798 | |
1799 | <pre><code>package Person; |
1800 | use Moose; |
1801 | |
1802 | has bank => ( |
1803 | is => 'rw', |
1804 | default => 'Spire FCU', |
1805 | );</code></pre> |
1806 | </div> |
1807 | |
1808 | <div class="slide"> |
1809 | <h1>Default</h1> |
1810 | |
1811 | <ul> |
1812 | <li>Can be a subroutine reference</li> |
1813 | </ul> |
1814 | |
1815 | <pre><code>package Person; |
1816 | use Moose; |
1817 | |
1818 | has bank => ( |
1819 | is => 'rw', |
1820 | default => |
1821 | sub { Bank->new( |
1822 | name => 'Spire FCU' ) }, |
1823 | );</code></pre> |
1824 | </div> |
1825 | |
1826 | <div class="slide"> |
debc93f8 |
1827 | <h1>Subroutine Reference Default</h1> |
8d1ce1d7 |
1828 | |
1829 | <ul> |
1830 | <li>Called as a method on the object</li> |
1831 | <li>Called anew for each object</li> |
1832 | </ul> |
1833 | </div> |
1834 | |
1835 | <div class="slide"> |
1836 | <h1>Why No Other Reference Types?</h1> |
1837 | |
1838 | <pre><code>package Person; |
1839 | use Moose; |
1840 | |
1841 | has bank => ( |
1842 | is => 'rw', |
1843 | <span class="wrong">default => Bank->new( |
1844 | name => 'Spire FCU' ),</span> |
1845 | );</code></pre> |
1846 | |
1847 | <ul> |
1848 | <li>Now <strong>every</strong> person shares the <strong>same</strong> Bank object!</li> |
1849 | </ul> |
1850 | </div> |
1851 | |
1852 | <div class="slide"> |
1853 | <h1>Defaulting to an Empty Reference</h1> |
1854 | |
1855 | <pre><code>package Person; |
1856 | use Moose; |
1857 | |
1858 | has packages => ( |
1859 | is => 'rw', |
1860 | default => <span class="highlight">sub { [] }</span>, |
1861 | );</code></pre> |
1862 | </div> |
1863 | |
1864 | <div class="slide"> |
1865 | <h1>What if I Want to Share?</h1> |
1866 | |
1867 | <pre><code>package Person; |
1868 | use Moose; |
1869 | |
1870 | my $highlander_bank = |
78c5b76a |
1871 | Bank->new( |
1872 | name => 'Clan MacLeod Trust' ); |
8d1ce1d7 |
1873 | |
1874 | has bank => ( |
1875 | is => 'rw', |
1876 | default => sub { $highlander_bank }, |
1877 | );</code></pre> |
1878 | </div> |
1879 | |
1880 | <div class="slide"> |
1881 | <h1>Builder</h1> |
1882 | |
1883 | <ul> |
78c5b76a |
1884 | <li>A method <em>name</em></li> |
6960f4e1 |
1885 | <li>When called, this method returns the default value</li> |
8d1ce1d7 |
1886 | </ul> |
1887 | </div> |
1888 | |
1889 | <div class="slide"> |
1890 | <h1>Builder</h1> |
1891 | |
1892 | <pre><code>package Person; |
1893 | use Moose; |
1894 | |
1895 | has bank => ( |
1896 | is => 'rw', |
1897 | builder => '_build_bank', |
1898 | ); |
1899 | |
1900 | sub _build_bank { |
1901 | my $self = shift; |
debc93f8 |
1902 | return Bank->new( |
1903 | name => 'Spire FCU' ); |
8d1ce1d7 |
1904 | }</code></pre> |
1905 | </div> |
1906 | |
1907 | <div class="slide"> |
1908 | <h1>Default vs Builder</h1> |
1909 | |
1910 | <ul> |
1911 | <li>Use default for simple scalars</li> |
1912 | <li>Use default to return empty references</li> |
1913 | <li>Use default for <em>very</em> trivial subroutine references</li> |
1914 | <li>Use builder for everything else</li> |
1915 | </ul> |
1916 | </div> |
1917 | |
1918 | <div class="slide"> |
1919 | <h1>Builder Bonuses</h1> |
1920 | |
1921 | <ul> |
1922 | <li>Can be overridden and method modified, because it's called by <em>name</em></li> |
1923 | <li>Roles can require a builder</li> |
1924 | </ul> |
1925 | </div> |
1926 | |
1927 | <div class="slide"> |
1928 | <h1>Role Requires Builder</h1> |
1929 | |
1930 | <pre><code>package HasBank; |
1931 | use Moose::Role; |
1932 | |
1933 | requires '_build_bank'; |
1934 | |
1935 | has bank => ( |
1936 | is => 'ro', |
1937 | builder => '_build_bank', |
1938 | );</code></pre> |
1939 | </div> |
1940 | |
1941 | <div class="slide"> |
debc93f8 |
1942 | <h1>Lazy, Good for Nothin' Attributes</h1> |
8d1ce1d7 |
1943 | |
1944 | <ul> |
1945 | <li>Normally, defaults are generated during object construction</li> |
1946 | <li>This can be expensive</li> |
1947 | <li>We want to default to <code>$self->size * 2</code>, but attribute initialization order is unpredictable</li> |
1948 | <li>Use lazy attributes!</li> |
1949 | </ul> |
1950 | </div> |
1951 | |
1952 | <div class="slide"> |
1953 | <h1>The Power of Dynamic Defaults</h1> |
1954 | |
1955 | <pre><code>package Person; |
1956 | use Moose; |
1957 | |
1958 | has shoe_size => ( |
6960f4e1 |
1959 | is => 'ro', |
1960 | required => 'ro', |
8d1ce1d7 |
1961 | );</code></pre> |
1962 | </div> |
1963 | |
1964 | <div class="slide"> |
1965 | <h1>The Power of Dynamic Defaults</h1> |
1966 | |
1967 | <pre><code>has shoes => ( |
1968 | is => 'ro', |
1969 | <span class="highlight">lazy => 1,</span> |
1970 | builder => '_build_shoes', |
1971 | ); |
1972 | |
1973 | sub _build_shoes { |
1974 | my $self = shift; |
1975 | |
1976 | return Shoes->new( |
13cb03c7 |
1977 | size => <span class="highlight">$self->shoe_size</span> ); |
8d1ce1d7 |
1978 | }</code></pre> |
1979 | </div> |
1980 | |
1981 | <div class="slide"> |
1982 | <h1>Lazy is Good</h1> |
1983 | |
1984 | <ul> |
1985 | <li>Lazy defaults are executed when the attribute is read</li> |
1986 | <li>Can see other object attributes</li> |
1987 | <li>Still need to watch out for circular laziness</li> |
1988 | </ul> |
1989 | </div> |
1990 | |
1991 | <div class="slide"> |
1992 | <h1>Clearer and Predicate</h1> |
1993 | |
1994 | <ul> |
1995 | <li>Attributes can have a value, including <code>undef</code>, or not</li> |
1996 | <li>Can clear the value with a clearer method</li> |
1997 | <li>Can check for the existence of a value with a predicate method</li> |
1998 | <li>By default, these methods are not created</li> |
1999 | </ul> |
2000 | </div> |
2001 | |
2002 | <div class="slide"> |
2003 | <h1>Clearer and Predicate</h1> |
2004 | |
2005 | <pre><code>package Person; |
2006 | use Moose; |
2007 | |
2008 | has account => ( |
2009 | is => 'ro', |
2010 | lazy => 1, |
2011 | builder => '_build_account', |
2012 | <span class="highlight">clearer => '_clear_account', |
2013 | predicate => 'has_account',</span> |
2014 | );</code></pre> |
2015 | </div> |
2016 | |
2017 | <div class="slide"> |
2018 | <h1>Clearer and Lazy Defaults</h1> |
2019 | |
2020 | <ul> |
2021 | <li>Lazy defaults are good for computed attributes</li> |
2022 | <li>Clear the attribute when the source data changes</li> |
2023 | <li>Recalculated at next access</li> |
2024 | </ul> |
2025 | </div> |
2026 | |
2027 | <div class="slide"> |
2028 | <h1>Renaming constructor arguments</h1> |
2029 | |
2030 | <ul> |
2031 | <li>By default, constructor names = attribute names</li> |
2032 | <li>Use <code>init_arg</code> to change this</li> |
2033 | <li>Set <code>init_arg => undef</code> to make it unconstructable</li> |
2034 | </ul> |
2035 | </div> |
2036 | |
2037 | <div class="slide"> |
2038 | <h1>Some <code>init_arg</code> examples</h1> |
2039 | |
2040 | <pre><code>package Person; |
2041 | use Moose; |
2042 | |
2043 | has shoe_size => ( |
2044 | is => 'ro', |
2045 | <span class="highlight">init_arg => 'foot_size',</span> |
2046 | ); |
2047 | |
2048 | Person->new( <span class="wrong">shoe_size => 13</span> ); |
2049 | |
2050 | my $person = |
2051 | Person->new( <span class="right">foot_size => 13</span> ); |
2052 | print $person->shoe_size;</code></pre> |
2053 | </div> |
2054 | |
2055 | <div class="slide"> |
2056 | <h1>Some <code>init_arg</code> examples</h1> |
2057 | |
2058 | <pre><code>package Person; |
2059 | use Moose; |
2060 | |
2061 | has shoes => ( |
2062 | is => 'ro', |
2063 | <span class="highlight">init_arg => undef,</span> |
2064 | ); |
2065 | |
2066 | Person->new( <span class="wrong">shoes => Shoes->new</span> );</code></pre> |
2067 | </div> |
2068 | |
2069 | <div class="slide"> |
2070 | <h1>Why Set <code>init_arg => undef</code>?</h1> |
2071 | |
2072 | <ul> |
2073 | <li>Use this with a lazy default for attributes-as-cache</li> |
2074 | <li>Compute the value as needed</li> |
2075 | <li>Ensure that it is always generated correctly (not set by constructor)</li> |
2076 | <li>Use triggers or method modifiers (coming soon) to clear the value</li> |
2077 | </ul> |
2078 | </div> |
2079 | |
2080 | <div class="slide"> |
2081 | <h1>Attribute Inheritance</h1> |
2082 | |
2083 | <ul> |
2084 | <li>By default, subclasses inherit attribute as-is</li> |
2085 | <li>Can change some attribute parameters in subclasses |
2086 | <ul> |
2087 | <li>default</li> |
2088 | <li>builder</li> |
2089 | <li>required</li> |
2090 | <li>lazy</li> |
2091 | <li>others we've not yet covered</li> |
2092 | </ul> |
2093 | </li> |
2094 | </ul> |
2095 | </div> |
2096 | |
2097 | <div class="slide"> |
2098 | <h1>Attribute Inheritance Example</h1> |
2099 | |
2100 | <pre><code>package Employee; |
2101 | use Moose; |
2102 | |
2103 | extends 'Person'; |
2104 | |
2105 | has '<span class="highlight">+first_name</span>' => ( |
2106 | default => 'Joe', |
2107 | );</code></pre> |
2108 | </div> |
2109 | |
2110 | <div class="slide"> |
2111 | <h1>Attribute Inheritance Warning</h1> |
2112 | |
2113 | <ul> |
2114 | <li>An attribute is a contract about a class's API</li> |
2115 | <li>Don't break that contract in a subclass</li> |
2116 | <li>Especially important in the context of types</li> |
2117 | </ul> |
2118 | </div> |
2119 | |
2120 | <div class="slide"> |
2121 | <h1>Changing Accessor Names</h1> |
2122 | |
2123 | <pre><code>package Person; |
2124 | use Moose; |
2125 | |
2126 | has first_name => ( |
bd857054 |
2127 | <span class="highlight">accessor</span> => 'first_name', |
8d1ce1d7 |
2128 | );</code></pre> |
2129 | |
2130 | <ul> |
2131 | <li>The long-hand version of <code>is => 'rw'</code></li> |
2132 | </ul> |
2133 | </div> |
2134 | |
2135 | <div class="slide"> |
2136 | <h1>Changing Accessor Names</h1> |
2137 | |
2138 | <pre><code>package Person; |
2139 | use Moose; |
2140 | |
2141 | has first_name => ( |
2142 | <span class="highlight">reader</span> => 'first_name', |
2143 | <span class="highlight">writer</span> => undef, |
2144 | );</code></pre> |
2145 | |
2146 | <ul> |
2147 | <li>The long-hand version of <code>is => 'ro'</code></li> |
2148 | </ul> |
2149 | </div> |
2150 | |
2151 | |
2152 | <div class="slide"> |
2153 | <h1>Changing Accessor Names</h1> |
2154 | |
2155 | <pre><code>package Person; |
2156 | use Moose; |
2157 | |
2158 | has first_name => ( |
2159 | <span class="highlight">reader</span> => 'get_first_name', |
de668480 |
2160 | <span class="highlight">writer</span> => 'set_first_name', |
8d1ce1d7 |
2161 | );</code></pre> |
2162 | </div> |
2163 | |
2164 | <div class="slide"> |
2165 | <h1>Changing Accessor Names</h1> |
2166 | |
2167 | <pre><code>package Person; |
2168 | use Moose; |
2169 | |
2170 | has first_name => ( |
2171 | <span class="highlight">is</span> => 'rw', |
2172 | <span class="highlight">writer</span> => '_first_name', |
2173 | );</code></pre> |
2174 | |
2175 | <ul> |
be6689d2 |
2176 | <li>Can also mix-and-match <code>is</code> and explicit names</li> |
8d1ce1d7 |
2177 | </ul> |
2178 | </div> |
2179 | |
2180 | <div class="slide"> |
2181 | <h1>ETOOMUCHTYPING</h1> |
2182 | |
2183 | <ul> |
2184 | <li><code>MooseX::FollowPBP</code><br /><code>get_foo</code> and <code>set_foo</code></li> |
2185 | <li><code>MooseX::SemiAffordanceAccessor</code><br /><code>foo</code> and <code>set_foo</code></li> |
2186 | </ul> |
2187 | </div> |
2188 | |
2189 | <div class="slide"> |
2190 | <h1>ETOOMUCHTYPING</h1> |
2191 | |
2192 | <pre><code>package Person; |
2193 | use Moose; |
2194 | <span class="highlight">use MooseX::SemiAffordanceAccessor;</span> |
2195 | |
2196 | has first_name => ( |
2197 | is => 'rw', |
2198 | );</code></pre> |
2199 | |
2200 | <ul> |
2201 | <li>Creates <code>first_name</code> and <code>set_first_name</code></li> |
2202 | </ul> |
2203 | </div> |
2204 | |
2205 | <div class="slide"> |
26164c8d |
2206 | <h1>Basic Attributes Summary</h1> |
2207 | |
2208 | <ul> |
2209 | <li>Attributes can be <code>required</code></li> |
2210 | <li>Attributes can have a <code>default</code> or <code>builder</code></li> |
2211 | <li>Attributes with a default or builder can be <code>lazy</code></li> |
2212 | <li>Attributes can have a <code>clearer</code> and/or <code>predicate</code></li> |
78c5b76a |
2213 | </ul> |
2214 | </div> |
2215 | |
2216 | <div class="slide"> |
2217 | <h1>Basic Attributes Summary</h1> |
2218 | |
2219 | <ul> |
26164c8d |
2220 | <li>An attribute's constructor name can be changed with <code>init_arg</code></li> |
2221 | <li>A subclass can alter its parents' attributes</li> |
2222 | <li>Attribute accessor names can be changed</li> |
2223 | </ul> |
2224 | </div> |
2225 | |
2226 | <div class="slide"> |
2227 | <h1>Questions?</h1> |
2228 | </div> |
2229 | |
2230 | <div class="slide"> |
8d1ce1d7 |
2231 | <h1>Exercises</h1> |
2232 | |
2233 | <pre># cd exercises |
debc93f8 |
2234 | # perl bin/prove -lv \ |
2235 | t/03-basic-attributes.t |
8d1ce1d7 |
2236 | |
2237 | Iterate til this passes all its tests</pre> |
2238 | </div> |
2239 | |
26164c8d |
2240 | <div class="slide fake-slide0"> |
2241 | <h1>Part 4: Method Modifiers</h1> |
2242 | </div> |
2243 | |
2244 | <div class="slide"> |
2245 | <h1>What is a Method Modifier</h1> |
2246 | |
2247 | <ul> |
2248 | <li>Apply to an existing method</li> |
78c5b76a |
2249 | <li>... that comes from a parent class, the current class, or a role</li> |
26164c8d |
2250 | <li>Roles can provide modifiers that are applied at composition time</li> |
2251 | </ul> |
2252 | </div> |
2253 | |
2254 | <div class="slide"> |
78c5b76a |
2255 | <h1>What Are Method Modifiers For?</h1> |
26164c8d |
2256 | |
2257 | <ul> |
0a0c7e7c |
2258 | <li>"Inject" behavior</li> |
26164c8d |
2259 | <li>Add behavior to generated methods (accessors, delegations)</li> |
78c5b76a |
2260 | <li>Added from a role, can modify existing behavior</li> |
26164c8d |
2261 | </ul> |
2262 | </div> |
2263 | |
2264 | <div class="slide"> |
2265 | <h1>Before and After</h1> |
2266 | |
2267 | <ul> |
2268 | <li>Simplest modifiers - <code>before</code> and <code>after</code></li> |
2269 | <li>Guess when they run!</li> |
2270 | </ul> |
2271 | </div> |
2272 | |
2273 | <div class="slide"> |
2274 | <h1>Uses for <code>before</code></h1> |
2275 | |
2276 | <ul> |
2277 | <li>As a pre-call check</li> |
2278 | </ul> |
2279 | |
2280 | <pre><code>package Person; |
2281 | use Moose; |
2282 | |
2283 | before work => sub { |
2284 | my $self = shift; |
2285 | die 'I have no job!' |
2286 | unless $self->has_title; |
2287 | };</code></pre> |
2288 | </div> |
2289 | |
2290 | <div class="slide"> |
2291 | <h1>Uses for <code>before</code></h1> |
2292 | |
2293 | <ul> |
2294 | <li>Logging/Debugging</li> |
2295 | </ul> |
2296 | |
2297 | <pre><code>package Person; |
2298 | use Moose; |
2299 | |
2300 | before work => sub { |
2301 | my $self = shift; |
2302 | return unless $DEBUG; |
2303 | |
debc93f8 |
2304 | warn "Called work on ", |
2305 | $self->full_name, |
26164c8d |
2306 | "with the arguments: [@_]\n"; |
2307 | };</code></pre> |
2308 | </div> |
2309 | |
2310 | <div class="slide"> |
2311 | <h1>Uses for <code>after</code></h1> |
2312 | |
2313 | <ul> |
2314 | <li>Also works for logging/debugging</li> |
2315 | <li>Post-X side-effects (recording audit info)</li> |
2316 | </ul> |
2317 | |
2318 | <pre><code>package Person; |
2319 | use Moose; |
2320 | |
2321 | after work => sub { |
2322 | my $self = shift; |
2323 | $self->work_count( |
2324 | $self->work_count + 1 ); |
2325 | };</code></pre> |
2326 | </div> |
2327 | |
2328 | <div class="slide"> |
2329 | <h1>Other Uses</h1> |
2330 | |
2331 | <ul> |
2332 | <li>Modifiers are useful for adding behavior to generated methods</li> |
2333 | </ul> |
2334 | </div> |
2335 | |
2336 | <div class="slide"> |
debc93f8 |
2337 | <h1>More Modifier Examples</h1> |
26164c8d |
2338 | |
2339 | <pre><code>has password => ( |
2340 | is => 'rw', |
2341 | clearer => 'clear_password', |
2342 | ); |
26164c8d |
2343 | has hashed_password => ( |
2344 | is => 'ro', |
2345 | builder => '_build_hashed_password', |
2346 | clearer => '_clear_hashed_password', |
2347 | ); |
26164c8d |
2348 | after clear_password => sub { |
2349 | my $self = shift; |
2350 | $self->_clear_hashed_password; |
2351 | };</code></pre> |
2352 | </div> |
2353 | |
2354 | <div class="slide"> |
2355 | <h1><code>before</code> and <code>after</code> Limitations</h1> |
2356 | |
2357 | <ul> |
2358 | <li>Cannot alter method parameters</li> |
2359 | <li>Cannot alter return value</li> |
2360 | <li>But <strong>can</strong> throw an exception</li> |
2361 | </ul> |
2362 | </div> |
2363 | |
2364 | <div class="slide"> |
2365 | <h1>The <code>around</code> Modifier</h1> |
2366 | |
2367 | <ul> |
2368 | <li>The big gun</li> |
2369 | <li>Can alter parameters <strong>and/or</strong> return values</li> |
2370 | <li>Can skip calling the wrapped method entirely</li> |
2371 | </ul> |
2372 | </div> |
2373 | |
2374 | <div class="slide"> |
2375 | <h1>The power of <code>around</code></h1> |
2376 | |
2377 | <pre><code>around insert => sub { |
2378 | my $orig = shift; |
2379 | my $self = shift; |
2380 | |
2381 | $self->_validate_insert(@_); |
2382 | |
2383 | my $new_user = |
2384 | $self->$orig( |
2385 | $self->_munge_insert(@_) ); |
2386 | |
2387 | $new_user->_assign_uri; |
26164c8d |
2388 | return $new_user; |
2389 | };</code></pre> |
2390 | </div> |
2391 | |
2392 | <div class="slide"> |
2393 | <h1>Modifier Order</h1> |
2394 | |
2395 | <ul> |
e5792e20 |
2396 | <li>Before runs in order from last to first</li> |
26164c8d |
2397 | <li>After runs in order from first to last</li> |
2398 | <li>Around runs in order from last to first</li> |
2399 | </ul> |
2400 | </div> |
2401 | |
2402 | <div class="slide"> |
2403 | <h1>Modifier Order Illustrated</h1> |
2404 | |
2405 | <pre> |
2406 | <span class="current incremental">before 2 |
2407 | before 1</span> |
2408 | <span class="incremental">around 2 |
2409 | around 1</span> |
2410 | <span class="incremental">wrapped method</span> |
2411 | <span class="incremental">around 1 |
2412 | around 2</span> |
2413 | <span class="incremental">after 1 |
2414 | after 2</span> |
2415 | </pre> |
2416 | </div> |
2417 | |
2418 | <div class="slide"> |
2419 | <h1>Modifiers in Roles</h1> |
2420 | |
2421 | <ul> |
2422 | <li>Roles can use these modifiers</li> |
2423 | <li>Very powerful!</li> |
2424 | </ul> |
2425 | </div> |
2426 | |
2427 | <div class="slide"> |
2428 | <h1>Modifiers in Roles</h1> |
2429 | |
2430 | <pre><code>package IsUnreliable; |
2431 | use Moose::Role; |
2432 | |
2433 | <span class="highlight">requires 'run'; |
2434 | |
2435 | around run</span> => sub { |
2436 | my $orig = shift; |
2437 | my $self = shift; |
2438 | |
2439 | return if rand(1) < 0.5; |
2440 | |
2441 | return $self->$orig(@_); |
2442 | };</code></pre> |
2443 | </div> |
2444 | |
2445 | <div class="slide"> |
2446 | <h1>Augment and Inner</h1> |
2447 | |
2448 | <ul> |
2449 | <li>Inverted <code>super</code></li> |
2450 | <li>From least- to most-specific</li> |
78c5b76a |
2451 | <li>Like Mason's autohandler feature</li> |
26164c8d |
2452 | <li>Grandparent to parent to child</li> |
2453 | <li>Not allowed in roles</li> |
2454 | </ul> |
2455 | </div> |
2456 | |
2457 | <div class="slide"> |
2458 | <h1>Augment and Inner</h1> |
2459 | |
2460 | <pre><code>package Document; |
2461 | |
2462 | sub xml { '<doc>' . <span class="highlight">inner()</span> . '</doc>' } |
2463 | |
2464 | package Report; |
2465 | extends 'Document'; |
c3ccfa10 |
2466 | <span class="highlight">augment xml</span> => |
2467 | sub { title() . <span class="highlight">inner()</span> . summary() }; |
26164c8d |
2468 | |
2469 | package TPSReport; |
2470 | extends 'Report'; |
c3ccfa10 |
2471 | <span class="highlight">augment xml</span> => |
2472 | sub { tps_xml() . <span class="highlight">inner()</span> };</code></pre> |
26164c8d |
2473 | </div> |
2474 | |
2475 | <div class="slide"> |
2476 | <h1>Augment and Inner</h1> |
2477 | |
2478 | <ul> |
2479 | <li>When we call <code>$tps->xml</code> ... |
2480 | <ul> |
2481 | <li><code>Document->xml</code></li> |
2482 | <li><code>Report->xml</code></li> |
2483 | <li><code>TPSReport->xml</code></li> |
2484 | </ul> |
2485 | </li> |
2486 | </ul> |
2487 | </div> |
2488 | |
2489 | <div class="slide"> |
2490 | <h1>Augment and Inner Usage</h1> |
2491 | |
2492 | <ul> |
2493 | <li>Call <code>inner()</code> to "fill in the blank"</li> |
2494 | <li>Requires designing for subclassing</li> |
2495 | <li>Call <code>inner()</code> in the terminal class, just in case</li> |
2496 | </ul> |
2497 | </div> |
2498 | |
2499 | <div class="slide"> |
5d572684 |
2500 | <h1>Method Modifiers Summary</h1> |
2501 | |
2502 | <ul> |
2503 | <li>Use <code>before</code> and <code>after</code> for ... |
2504 | <ul> |
2505 | <li>logging</li> |
2506 | <li>pre- or post-validation</li> |
2507 | <li>to add behavior to generated methods</li> |
2508 | </ul> |
2509 | </li> |
2510 | <li>These two modifiers cannot change parameters or return values</li> |
2511 | </ul> |
2512 | </div> |
2513 | |
2514 | <div class="slide"> |
2515 | <h1>Method Modifiers Summary</h1> |
2516 | |
2517 | <ul> |
2518 | <li>Use <code>around</code> to ... |
2519 | <ul> |
2520 | <li>alter parameters passed to the original method</li> |
2521 | <li>alter the return value of the original method</li> |
2522 | <li>not call the original method at all (or call a <em>different</em> method)</li> |
2523 | </ul> |
2524 | </li> |
2525 | </ul> |
2526 | </div> |
2527 | |
2528 | <div class="slide"> |
2529 | <h1>Method Modifiers Summary</h1> |
2530 | |
2531 | <ul> |
2532 | <li>When using modifiers in a role, require the modified method</li> |
2533 | <li>Use <code>augment</code> and <code>inner</code> to invert the normal subclassing flow ... |
2534 | <ul> |
2535 | <li>Least- to most-specific (parents to children)</li> |
2536 | <li>Build in "insertability" (stick more stuff in the "middle")</li> |
2537 | </ul> |
2538 | </li> |
2539 | <li>Always call <code>inner</code> in the most specific subclass to allow for future extension</li> |
2540 | </ul> |
2541 | </div> |
2542 | |
2543 | <div class="slide"> |
26164c8d |
2544 | <h1>Questions?</h1> |
2545 | </div> |
2546 | |
2547 | <div class="slide"> |
2548 | <h1>Exercises</h1> |
2549 | |
2550 | <pre># cd exercises |
debc93f8 |
2551 | # perl bin/prove -lv \ |
2552 | t/04-method-modifiers.t |
26164c8d |
2553 | |
2554 | Iterate til this passes all its tests</pre> |
2555 | </div> |
2556 | |
5d572684 |
2557 | <div class="slide fake-slide0"> |
2558 | <h1>Part 5: Types</h1> |
2559 | </div> |
2560 | |
636ceec1 |
2561 | <div class="slide"> |
2562 | <h1>A Type System for Perl</h1> |
2563 | |
2564 | <ul> |
2565 | <li>Sort of ...</li> |
2566 | <li><em>Variables</em> are not typed</li> |
2567 | <li>Attributes can have types</li> |
2568 | <li>MooseX modules let you define method signatures</li> |
2569 | </ul> |
2570 | </div> |
2571 | |
2572 | <div class="slide"> |
2573 | <h1>Components of a Moose Type</h1> |
2574 | |
2575 | <ul> |
2576 | <li>A type is a name and a constraint</li> |
2577 | <li>Types have a hierarchy</li> |
2578 | <li>Constraints are cumulative from parents</li> |
2579 | <li>Types can have associated coercions</li> |
2580 | </ul> |
2581 | </div> |
2582 | |
2583 | <div class="slide"> |
2584 | <h1>Built-in Type Hierarchy</h1> |
2585 | |
2586 | <pre> |
2587 | Any |
2588 | Item |
2589 | Bool |
2590 | Maybe[`a] |
2591 | Undef |
2592 | Defined |
2593 | Value |
78c5b76a |
2594 | Str |
2595 | Num |
2596 | Int |
2597 | ClassName |
636ceec1 |
2598 | </pre> |
2599 | </div> |
2600 | |
2601 | <div class="slide"> |
2602 | <h1>Built-in Type Hierarchy</h1> |
2603 | |
2604 | <pre> |
2605 | (Item) |
2606 | (Defined) |
b9a2a53f |
2607 | (Value) |
636ceec1 |
2608 | Ref |
2609 | ScalarRef |
2610 | ArrayRef[`a] |
2611 | HashRef[`a] |
2612 | CodeRef |
2613 | RegexpRef |
2614 | GlobRef |
78c5b76a |
2615 | FileHandle |
636ceec1 |
2616 | Object |
2617 | </pre> |
2618 | </div> |
2619 | |
2620 | <div class="slide"> |
2621 | <h1>Bool</h1> |
2622 | |
2623 | <h2>True</h2> |
2624 | <pre><code>1 |
2625 | 924.1 |
2626 | 'true' |
2627 | {}</code></pre> |
2628 | |
2629 | <h2>False</h2> |
2630 | <pre><code>0 |
2631 | 0.0 |
2632 | '0' |
2633 | undef</code></pre> |
2634 | |
2635 | <ul> |
2636 | <li>Like Perl's <code>if ($foo)</code></li> |
2637 | </ul> |
2638 | </div> |
2639 | |
2640 | <div class="slide"> |
2641 | <h1>Value (and subtypes)</h1> |
2642 | |
2643 | <ul> |
b59551bc |
2644 | <li><code>Value</code> is true when <code>! ref $thing</code></li> |
2645 | <li><code>Value</code> and <code>Str</code> are effectively the same, but <code>Str</code> is more expressive</li> |
84326b8a |
2646 | <li><code>Num</code> is true when a <code>$scalar</code> looks like a number</li> |
636ceec1 |
2647 | <li>An overloaded object which numifies does not pass the <code>Num</code> constraint!</li> |
2648 | <li>Perl 5's overloading is hopelessly broken</li> |
2649 | </ul> |
2650 | </div> |
2651 | |
2652 | <div class="slide"> |
2653 | <h1>ClassName and RoleName</h1> |
2654 | |
2655 | <ul> |
2656 | <li>A string with a package name</li> |
2657 | <li>The package <strong>must already be loaded</strong></li> |
2658 | </ul> |
2659 | </div> |
2660 | |
2661 | <div class="slide"> |
2662 | <h1>Parameterizable Types</h1> |
2663 | |
2664 | <ul> |
2665 | <li>What does <code>ArrayRef[`a]</code> mean?</li> |
2666 | <li><code>s/`a/Int/</code> (or <code>Str</code> or ...)</li> |
2667 | <li>When you use it you can write ... |
2668 | <ul> |
2669 | <li><code>ArrayRef</code> (== <code>ArrayRef[Item]</code>)</li> |
2670 | <li><code>ArrayRef[Str]</code></li> |
2671 | <li><code>ArrayRef[MyTypeName]</code></li> |
2672 | <li><code>ArrayRef[HashRef[Maybe[Int]]]</code></li> |
2673 | </ul> |
2674 | </li> |
2675 | </ul> |
2676 | </div> |
2677 | |
2678 | <div class="slide"> |
2679 | <h1>Maybe[`a]</h1> |
2680 | |
2681 | <ul> |
2682 | <li>Maybe means either the named type or <code>undef</code></li> |
2683 | <li><code>Maybe[Int]</code> accepts integers or <code>undef</code></li> |
2684 | </ul> |
2685 | </div> |
2686 | |
2687 | <div class="slide"> |
b59551bc |
2688 | <h1>Type Union</h1> |
636ceec1 |
2689 | |
2690 | <ul> |
2691 | <li>This or that (or that or ...)</li> |
2692 | <li><code>Int | ArrayRef[Int]</code></li> |
2693 | <li>But use a coercion instead when possible</li> |
b59551bc |
2694 | <li>Or use a <code>role_type</code>, <code>duck_type</code>, or anything not a union</li> |
2695 | <li>A union is often a code smell</li> |
636ceec1 |
2696 | </ul> |
2697 | </div> |
2698 | |
2699 | <div class="slide"> |
2700 | <h1>Making Your Own Types</h1> |
2701 | |
2702 | <pre><code>use Moose::Util::TypeConstraints; |
2703 | |
2704 | <span class="incremental current">subtype 'PositiveInt',</span> |
2705 | <span class="incremental">as 'Int',</span> |
2706 | <span class="incremental">where { $_ > 0 },</span> |
debc93f8 |
2707 | <span class="incremental">message |
2708 | { "The value you provided ($_)" |
2709 | . " was not a positive int." };</span> |
636ceec1 |
2710 | |
2711 | has size => ( |
2712 | is => 'ro', |
2713 | <span class="incremental">isa => 'PositiveInt',</span> |
2714 | );</code></pre> |
2715 | </div> |
2716 | |
2717 | <div class="slide"> |
2718 | <h1>Automatic Types</h1> |
2719 | |
2720 | <ul> |
2721 | <li>Moose creates a type for every Moose class and role</li> |
2722 | <li>Unknown names are assumed to be classes</li> |
2723 | </ul> |
2724 | </div> |
2725 | |
2726 | <div class="slide"> |
2727 | <h1>Automatic Types</h1> |
2728 | |
2729 | <pre><code>package Employee; |
2730 | use Moose; |
2731 | |
2732 | has manager => ( |
2733 | is => 'rw', |
2734 | <span class="highlight">isa => 'Employee',</span> |
2735 | ); |
2736 | |
2737 | has start_date => ( |
2738 | is => 'ro', |
2739 | <span class="highlight">isa => 'DateTime',</span> |
2740 | );</code></pre> |
2741 | </div> |
2742 | |
2743 | <div class="slide"> |
2744 | <h1>Subtype Shortcuts - <code>class_type</code></h1> |
2745 | |
2746 | <pre><code>use Moose::Util::TypeConstraints; |
78c5b76a |
2747 | class_type 'DateTime';</code></pre> |
2748 | |
2749 | <hr /> |
636ceec1 |
2750 | |
78c5b76a |
2751 | <pre><code>subtype 'DateTime', |
636ceec1 |
2752 | as 'Object', |
2753 | where { $_->isa('DateTime') }, |
2754 | message { ... };</code></pre> |
2755 | </div> |
2756 | |
2757 | <div class="slide"> |
2758 | <h1>Subtype Shortcuts - <code>role_type</code></h1> |
2759 | |
2760 | <pre><code>use Moose::Util::TypeConstraints; |
78c5b76a |
2761 | role_type 'Printable';</coe></pre> |
636ceec1 |
2762 | |
78c5b76a |
2763 | <hr /> |
2764 | |
2765 | <pre><code>subtype 'Printable', |
636ceec1 |
2766 | as 'Object', |
2767 | where |
2768 | { Moose::Util::does_role( |
2769 | $_, 'Printable' ) }, |
2770 | message { ... };</code></pre> |
2771 | </div> |
2772 | |
2773 | <div class="slide"> |
2774 | <h1>Subtype Shortcuts - <code>duck_type</code></h1> |
2775 | |
2776 | <pre><code>use Moose::Util::TypeConstraints; |
78c5b76a |
2777 | duck_type Car => qw( run break_down );</code></pre> |
2778 | |
2779 | <hr /> |
636ceec1 |
2780 | |
78c5b76a |
2781 | <pre><code>subtype 'Car', |
636ceec1 |
2782 | as 'Object', |
2783 | where { all { $_->can($_) } |
2784 | qw( run break_down ) }, |
2785 | message { ... };</code></pre> |
2786 | </div> |
2787 | |
2788 | <div class="slide"> |
2789 | <h1>Subtype Shortcuts - <code>enum</code></h1> |
2790 | |
2791 | <pre><code>use Moose::Util::TypeConstraints; |
78c5b76a |
2792 | enum Color => qw( red blue green ) );</code></pre> |
2793 | |
2794 | <hr /> |
636ceec1 |
2795 | |
78c5b76a |
2796 | <pre><code>my %ok = map { $_ => 1 } |
debc93f8 |
2797 | qw( red blue green ); |
2798 | |
636ceec1 |
2799 | subtype 'Color' |
2800 | as 'Str', |
2801 | where { $ok{$_} }, |
2802 | message { ... };</code></pre> |
2803 | </div> |
2804 | |
2805 | <div class="slide"> |
2806 | <h1>Anonymous Subtypes</h1> |
2807 | |
2808 | <pre><code>package Person; |
2809 | |
2810 | <span class="highlight">my $posint = |
2811 | subtype as 'Int', where { $_ > 0 };</span> |
2812 | |
2813 | has size => ( |
2814 | is => 'ro', |
2815 | <span class="highlight">isa => $posint,</span> |
2816 | );</code></pre> |
2817 | |
2818 | <ul> |
2819 | <li>Shortcuts have anonymous forms as well</li> |
2820 | </ul> |
2821 | </div> |
2822 | |
2823 | <div class="slide"> |
2824 | <h1>Coercions</h1> |
2825 | |
2826 | <pre><code>use Moose::Util::TypeConstraints; |
2827 | |
2828 | subtype 'UCStr', |
2829 | as 'Str', |
debc93f8 |
2830 | where { ! /[a-z]/ };</code></pre> |
2831 | </div> |
2832 | |
2833 | <div class="slide"> |
2834 | <h1>Coercions</h1> |
636ceec1 |
2835 | |
debc93f8 |
2836 | <pre><code><span class="incremental current">coerce 'UCStr',</span> |
636ceec1 |
2837 | <span class="incremental">from 'Str',</span> |
2838 | <span class="incremental">via { uc };</span> |
2839 | |
2840 | has shouty_name => ( |
2841 | is => 'ro', |
2842 | isa => 'UCStr', |
2843 | <span class="incremental">coerce => 1,</span> |
2844 | );</code></pre> |
2845 | </div> |
2846 | |
2847 | <div class="slide"> |
b59551bc |
2848 | <h1>Coercion Examples</h1> |
2849 | |
2850 | <pre><code>subtype 'My::DateTime', |
2851 | as class_type 'DateTime'; |
2852 | |
2853 | coerce 'My::DateTime', |
2854 | from 'HashRef', |
2855 | via { DateTime->new( %{$_} ) }; |
2856 | |
2857 | coerce 'My::DateTime', |
2858 | from 'Int', |
2859 | via { DateTime->from_epoch( |
2860 | epoch => $_ ) };</code></pre> |
2861 | |
2862 | <ul> |
2863 | <li>Use coercion to inflate a value</li> |
2864 | </ul> |
2865 | </div> |
2866 | |
2867 | <div class="slide"> |
2868 | <h1>Coercion Examples</h1> |
2869 | |
2870 | <pre><code>coerce 'ArrayRef[Int]', |
2871 | from 'Int', |
2872 | via { [ $_ ] };</code></pre> |
2873 | |
2874 | <ul> |
4bb8a45d |
2875 | <li>Instead of union - <code style="white-space: nowrap">Int | ArrayRef[Int]</code></li> |
b59551bc |
2876 | </ul> |
2877 | </div> |
2878 | |
b59551bc |
2879 | <div class="slide"> |
2880 | <h1>Using Types with Attributes</h1> |
2881 | |
2882 | <pre><code>package Person; |
2883 | |
b59551bc |
2884 | has height => ( |
2885 | is => 'rw', |
2886 | <span class="highlight">isa => 'Num',</span> |
2887 | ); |
2888 | |
2889 | has favorite_numbers => ( |
2890 | is => 'rw', |
2891 | <span class="highlight">isa => 'ArrayRef[Int]', |
2892 | coerce => 1,</span> |
2893 | );</code></pre> |
2894 | </div> |
2895 | |
2896 | <div class="slide"> |
ee2e815e |
2897 | <h1>More Droppings</h1> |
2898 | |
2899 | <ul> |
0f55e69e |
2900 | <li><code>Moose::Util::TypeConstraints</code> also needs cleanup</li> |
ee2e815e |
2901 | </ul> |
2902 | |
2903 | <pre><code>package Person; |
2904 | |
2905 | use Moose; |
2906 | use Moose::Util::TypeConstraints; |
2907 | |
2908 | subtype ...; |
2909 | |
2910 | no Moose; |
2911 | <span class="highlight">no Moose::Util::TypeConstraints;</span></code></pre> |
2912 | </div> |
2913 | |
2914 | <div class="slide"> |
b59551bc |
2915 | <h1>Typed Methods (Low-tech)</h1> |
2916 | |
2917 | <pre class="medium"><code>package Person; |
2918 | <span class="highlight">use MooseX::Params::Validate qw( validated_list );</span> |
2919 | |
2920 | sub work { |
2921 | my $self = shift; |
2922 | <span class="highlight">my ( $tasks, $can_rest ) = |
2923 | validated_list( |
2924 | \@_, |
2925 | tasks => |
2926 | { isa => 'ArrayRef[Task]', |
64864ac0 |
2927 | coerce => 1 }, |
b59551bc |
2928 | can_rest => |
2929 | { isa => 'Bool', |
2930 | default => 0 }, |
2931 | );</span> |
b59551bc |
2932 | ... |
2933 | }</code></pre> |
68af922f |
2934 | </div> |
b59551bc |
2935 | |
2936 | <div class="slide"> |
2937 | <h1>Typed Methods (High-tech)</h1> |
2938 | |
2939 | <pre class="medium"><code>package Person; |
2940 | |
2941 | <span class="highlight">use MooseX::Method::Signatures;</span> |
2942 | |
2943 | <span class="highlight">method work ( ArrayRef[Task] :$tasks, |
2944 | Bool :$can_rest = 0 )</span> { |
2945 | my $self = shift; |
2946 | |
2947 | ... |
2948 | }</code></pre> |
68af922f |
2949 | </div> |
b59551bc |
2950 | |
2951 | <div class="slide"> |
636ceec1 |
2952 | <h1>Digression: The Type Registry</h1> |
2953 | |
2954 | <ul> |
0f55e69e |
2955 | <li>Types are actually <code>Moose::Meta::TypeConstraints</code> <em>objects</em></li> |
636ceec1 |
2956 | <li>Stored in an interpreter-global registry mapping names to objects</li> |
2957 | </ul> |
2958 | </div> |
2959 | |
2960 | <div class="slide"> |
2961 | <h1>Danger!</h1> |
2962 | |
2963 | <ul> |
2964 | <li>Coercions are attached to type objects</li> |
2965 | <li>Therefore also global</li> |
2966 | <li>Name conflicts between modules!</li> |
2967 | <li>Coercion conflicts between modules!</li> |
2968 | </ul> |
2969 | </div> |
2970 | |
2971 | <div class="slide"> |
b59551bc |
2972 | <h1>Namespace Fix</h1> |
636ceec1 |
2973 | |
2974 | <ul> |
2975 | <li>Use some sort of pseudo-namespacing scheme</li> |
2976 | <li>Never coerce directly to a class name, or <em>to</em> built-in types</li> |
2977 | </ul> |
2978 | </div> |
2979 | |
2980 | <div class="slide"> |
2981 | <h1>Namespace Fix</h1> |
2982 | |
2983 | <pre><code>use Moose::Util::TypeConstraints; |
636ceec1 |
2984 | subtype <span class="highlight">'MyApp::Type::DateTime',</span> |
2985 | as 'DateTime'; |
2986 | |
2987 | <span class="highlight">coerce 'MyApp::Type::DateTime',</span> |
2988 | from 'HashRef', |
2989 | via { DateTime->new( %{$_} ) } |
2990 | |
2991 | has creation_date => ( |
2992 | is => 'ro', |
2993 | <span class="highlight">isa => 'MyApp::Type::DateTime',</span> |
2994 | coerce => 1, |
2995 | );</code></pre> |
2996 | </div> |
2997 | |
2998 | <div class="slide"> |
2999 | <h1>Namespace Fix</h1> |
3000 | |
3001 | <pre><code>subtype 'MyApp::Type::ArrayOfInt', |
3002 | as 'ArrayRef[Int]'; |
3003 | |
3004 | coerce 'MyApp::Type::ArrayOfInt', |
3005 | from 'Int', |
3006 | via { [ $_ ] };</code></pre> |
3007 | </div> |
636ceec1 |
3008 | |
3009 | <div class="slide"> |
b59551bc |
3010 | <h1>Namespace Fix Pros and Cons</h1> |
636ceec1 |
3011 | |
b59551bc |
3012 | <ul> |
3013 | <li><span class="right">Relatively simple</span></li> |
3014 | <li><span class="right">Already built into Moose</span></li> |
3015 | <li><span class="wrong">Conflates type and module namespaces</span></li> |
3016 | <li><span class="wrong">Type names are strings, so typos are easy to make and may be hard to find</span></li> |
3017 | </ul> |
3018 | </div> |
636ceec1 |
3019 | |
b59551bc |
3020 | <div class="slide"> |
3021 | <h1>MooseX::Types</h1> |
636ceec1 |
3022 | |
b59551bc |
3023 | <pre><code>package MyApp::Types; |
3024 | |
3025 | use MooseX::Types |
3026 | <span class="highlight">-declare => [ qw( ArrayOfInt ) ]</span>; |
3027 | use MooseX::Types::Moose |
3028 | qw( ArrayRef Int ); |
3029 | |
3030 | subtype <span class="highlight">ArrayOfInt</span>, |
3031 | as ArrayRef[Int]; |
3032 | |
3033 | coerce <span class="highlight">ArrayOfInt</span> |
3034 | from Int, |
3035 | via { [ $_ ] };</code></pre> |
3036 | </div> |
3037 | |
3038 | <div class="slide"> |
3039 | <h1>MooseX::Types</h1> |
3040 | |
3041 | <pre><code>package MyApp::Account; |
3042 | |
3043 | use MyApp::Types qw( ArrayOfInt ); |
3044 | |
3045 | has transaction_history => ( |
3046 | is => 'rw', |
3047 | isa => ArrayOfInt, |
3048 | );</code></pre> |
68af922f |
3049 | </div> |
b59551bc |
3050 | |
3051 | <div class="slide"> |
3052 | <h1>MooseX::Types</h1> |
636ceec1 |
3053 | |
3054 | <ul> |
b59551bc |
3055 | <li>Type names are exported functions, catches typos early</li> |
3056 | <li>Types must be pre-declared</li> |
78c5b76a |
3057 | <li>Types are stored with namespaces internally, but you use short names</li> |
b59551bc |
3058 | <li>Import existing Moose types as functions from <code>MooseX::Types::Moose</code></li> |
3059 | <li>Still need string names for things like <code>ArrayRef['Email::Address']</code></li> |
636ceec1 |
3060 | </ul> |
3061 | </div> |
3062 | |
3063 | <div class="slide"> |
b59551bc |
3064 | <h1>MooseX::Types Pros and Cons</h1> |
636ceec1 |
3065 | |
b59551bc |
3066 | <ul> |
3067 | <li><span class="right">Catches typos at compile time</span></li> |
3068 | <li><span class="right">Automatic namespacing</span></li> |
3069 | <li><span class="wrong">One more thing to install and learn</span></li> |
78c5b76a |
3070 | <li><span class="wrong">Every name is typed twice (declared and then defined)</span></li> |
b59551bc |
3071 | <li><span class="wrong">Still stuck with strings when referring to class or role names</span></li> |
68af922f |
3072 | <li><span class="wrong">Coercion gotcha from earlier still applies to types exported from <code>MooseX::Types::Moose</code></span></li> |
b59551bc |
3073 | </ul> |
3074 | </div> |
3075 | |
3076 | <div class="slide"> |
3077 | <h1>Recommendation</h1> |
636ceec1 |
3078 | |
3079 | <ul> |
b59551bc |
3080 | <li>Use <code>MooseX::Types</code></li> |
3081 | <li>Compile time error catching and automatic namespacing are huge wins</li> |
3082 | <li>Docs from <code>Moose::Util::TypeConstraints</code> are 98% compatible with <code>MooseX::Types</code> anyway</li> |
3083 | <li>A function exported by a type library works wherever a type name would</li> |
636ceec1 |
3084 | </ul> |
3085 | </div> |
3086 | |
3087 | <div class="slide"> |
3088 | <h1>Questions?</h1> |
3089 | </div> |
3090 | |
3091 | <div class="slide"> |
3092 | <h1>Exercises</h1> |
3093 | |
3094 | <pre># cd exercises |
3095 | # perl bin/prove -lv t/05-types.t |
3096 | |
3097 | Iterate til this passes all its tests</pre> |
3098 | </div> |
3099 | |
5d572684 |
3100 | <div class="slide fake-slide0"> |
3101 | <h1>Part 6: Advanced Attributes</h1> |
3102 | </div> |
3103 | |
3104 | <div class="slide"> |
3105 | <h1>Weak References</h1> |
3106 | |
3107 | <ul> |
3108 | <li>A weak reference lets you avoid circular references</li> |
3109 | <li>Weak references do not increase the reference count</li> |
3110 | </ul> |
3111 | </div> |
3112 | |
3113 | <div class="slide"> |
3114 | <h1>Circular Reference Illustrated</h1> |
3115 | |
3116 | <pre><code>my $foo = {}; |
3117 | my $bar = { foo => $foo }; |
3118 | $foo->{bar} = $bar;</code></pre> |
3119 | |
3120 | <ul> |
3121 | <li>Neither <code>$foo</code> nor <code>$bar</code> go out of scope<br /> |
3122 | (until the program exits)</li> |
3123 | </ul> |
3124 | </div> |
3125 | |
3126 | <div class="slide"> |
3127 | <h1>Weakening Circular References</h1> |
3128 | |
3129 | <pre><code>use Scalar::Util qw( weaken ); |
3130 | |
3131 | my $foo = {}; |
3132 | my $bar = { foo => $foo }; |
3133 | $foo->{bar} = $bar; |
3134 | weaken $foo->{bar}</code></pre> |
3135 | |
3136 | <ul> |
3137 | <li>When <code>$bar</code> goes out of scope, <code>$foo->{bar}</code> becomes <code>undef</code></li> |
3138 | </ul> |
3139 | </div> |
3140 | |
3141 | <div class="slide"> |
3142 | <h1>Circular References in Attributes</h1> |
3143 | |
3144 | <pre><code>package Person; |
3145 | use Moose; |
3146 | |
3147 | has name => ( is => 'ro' ); |
3148 | has friend => ( is => 'rw' ); |
3149 | |
3150 | my $alice = Person->new( name => 'Alice' ); |
3151 | my $bob = Person->new( name => 'Bob' ); |
3152 | $bob->friend($alice); |
3153 | $alice->friend($bob);</code></pre> |
3154 | </div> |
3155 | |
3156 | <div class="slide"> |
3157 | <h1>The Fix</h1> |
3158 | |
3159 | <pre><code>package Person; |
3160 | use Moose; |
3161 | |
3162 | has name => ( is => 'ro' ); |
debc93f8 |
3163 | has friend => ( is => 'rw', |
3164 | <span class="highlight">weak_ref => 1</span> ); |
5d572684 |
3165 | |
3166 | my $alice = Person->new( name => 'Alice' ); |
3167 | my $bob = Person->new( name => 'Bob' ); |
3168 | $bob->friend($alice); |
3169 | $alice->friend($bob);</code></pre> |
3170 | </div> |
3171 | |
3172 | <div class="slide"> |
3173 | <h1>Under the Hood</h1> |
3174 | |
3175 | <ul> |
3176 | <li>A <code>weak_ref</code> attribute calls <code>weaken</code> ... |
3177 | <ul> |
3178 | <li>during object construction</li> |
3179 | <li>when the attribute is set via a writer</li> |
3180 | </ul> |
3181 | </li> |
3182 | </ul> |
3183 | </div> |
3184 | |
3185 | <div class="slide"> |
3186 | <h1>Triggers</h1> |
3187 | |
3188 | <ul> |
3189 | <li>A code reference run after an attribute is <em>set</em></li> |
3190 | <li>Like an <code>after</code> modifier, but makes intentions clearer</li> |
3191 | </ul> |
3192 | |
3193 | <h2 class="wrong">Gross</h2> |
3194 | |
3195 | <pre><code>after salary_level => { |
3196 | my $self = shift; |
78c5b76a |
3197 | <span class="highlight">return unless @_;</span> |
5d572684 |
3198 | $self->clear_salary; |
3199 | };</code></pre> |
3200 | </div> |
3201 | |
3202 | <div class="slide"> |
3203 | <h1>Use a Trigger Instead</h1> |
3204 | |
3205 | <h2 class="right">Cleaner</h2> |
3206 | |
3207 | <pre><code>has salary_level => ( |
3208 | is => 'rw', |
78c5b76a |
3209 | trigger => |
3210 | sub { $_[0]->clear_salary }, |
5d572684 |
3211 | );</code></pre> |
3212 | </div> |
3213 | |
3214 | <div class="slide"> |
3215 | <h1>Delegation</h1> |
3216 | |
3217 | <ul> |
3218 | <li>Attributes can be objects</li> |
3219 | <li>Delegation transparently calls methods on those objects</li> |
3220 | </ul> |
3221 | </div> |
3222 | |
3223 | <div class="slide"> |
3224 | <h1>Delegation Examples</h1> |
3225 | |
3226 | <pre><code>package Person; |
3227 | |
3228 | has lungs => ( |
3229 | is => 'ro', |
3230 | isa => 'Lungs', |
3231 | <span class="highlight">handles => [ 'inhale', 'exhale' ],</span> |
3232 | );</code></pre> |
3233 | |
3234 | <ul> |
3235 | <li>Creates <code>$person->inhale</code> and <code>->exhale</code> methods</li> |
3236 | <li>Internally calls <code>$person->lungs->inhale</code></li> |
3237 | </ul> |
3238 | </div> |
3239 | |
3240 | <div class="slide"> |
3241 | <h1>Why Delegation?</h1> |
3242 | |
3243 | <ul> |
3244 | <li>Reduce the number of classes exposed</li> |
3245 | <li>Re-arrange class internals -<br /> |
3246 | turn a method into an attribute with delegation</li> |
3247 | <li>Provide convenenience methods</li> |
3248 | </ul> |
3249 | </div> |
3250 | |
3251 | <div class="slide"> |
3252 | <h1>Moose's <code>handles</code> Parameter</h1> |
3253 | |
3254 | <ul> |
3255 | <li>Accepts many arguments ... |
3256 | <ul> |
3257 | <li>Array reference - list of methods to delegate as-is</li> |
3258 | <li>Hash reference - map of method names</li> |
3259 | <li>Regex - delegates all matching methods</li> |
3260 | <li>Role name - delegates all methods in the role</li> |
3261 | <li>Sub reference - does something complicated ;)</li> |
3262 | </ul> |
3263 | </li> |
3264 | </ul> |
3265 | </div> |
3266 | |
3267 | <div class="slide"> |
3268 | <h1>Array Reference</h1> |
3269 | |
3270 | <ul> |
78c5b76a |
3271 | <li>1-to-1 mapping</li> |
5d572684 |
3272 | <li>Takes each method name and creates a simple delegation from the delegating class to the delegatee attribute</li> |
3273 | </ul> |
3274 | </div> |
3275 | |
3276 | <div class="slide"> |
3277 | <h1>Hash Reference</h1> |
3278 | |
3279 | <ul> |
3280 | <li>Mapping of names in the delegating class to the delegatee class</li> |
3281 | </ul> |
3282 | |
3283 | <pre><code>package Person; |
3284 | use Moose; |
5d572684 |
3285 | has account => ( |
3286 | is => 'ro', |
3287 | isa => 'BankAccount', |
3288 | <span class="highlight">handles => { |
3289 | receive_money => 'deposit', |
3290 | give_money => 'withdraw', |
3291 | },</span> |
3292 | );</code></pre> |
3293 | </div> |
3294 | |
3295 | <div class="slide"> |
3296 | <h1>Hash Reference Detailed</h1> |
3297 | |
3298 | <pre><code> handles => { |
3299 | receive_money => 'deposit', |
3300 | give_money => 'withdraw', |
3301 | },</code></pre> |
3302 | |
3303 | <ul> |
3304 | <li><code>$person->receive_money</code> = <code>$person->account->deposit</code></li> |
3305 | <li><code>$person->give_money</code> = <code>$person->account->withdraw</code></li> |
3306 | </ul> |
3307 | </div> |
3308 | |
3309 | <div class="slide"> |
3310 | <h1>Regex</h1> |
3311 | |
3312 | <pre><code>package Person; |
3313 | use Moose; |
3314 | |
3315 | has name => ( |
3316 | is => 'ro', |
3317 | isa => 'Name', |
3318 | handles => qr/.*/, |
3319 | );</code></pre> |
3320 | |
3321 | <ul> |
3322 | <li>Creates a delegation for every method in the Name class</li> |
3323 | <li>Excludes <code>meta</code> and methods inherited from <code>Moose::Object</code></li> |
3324 | </ul> |
3325 | </div> |
3326 | |
3327 | <div class="slide"> |
3328 | <h1>Role Name</h1> |
3329 | |
3330 | <pre><code>package Auditor; |
3331 | use Moose::Role; |
5d572684 |
3332 | sub record_change { ... } |
3333 | sub change_history { ... } |
3334 | |
3335 | package Account; |
3336 | use Moose; |
3337 | |
3338 | has history => ( |
3339 | is => 'ro', |
3340 | does => 'Auditor', |
3341 | <span class="highlight">handles => 'Auditor',</span> |
3342 | );</code></pre> |
3343 | </div> |
3344 | |
3345 | <div class="slide"> |
3346 | <h1>Role Name Detailed</h1> |
3347 | |
3348 | <ul> |
3349 | <li>Account gets delegate methods for each method in the <code>Auditor</code> role |
3350 | <ul> |
3351 | <li>record_history</li> |
3352 | <li>change_history</li> |
3353 | </ul> |
3354 | </li> |
3355 | </ul> |
3356 | </div> |
3357 | |
3358 | <div class="slide"> |
1c32806a |
3359 | <h1>Native Delegation</h1> |
3360 | |
3361 | <ul> |
3362 | <li>Delegate to <em>unblessed</em> Perl types</li> |
3363 | <li>Scalar, array or hash ref, etc</li> |
ba3e6f3b |
3364 | <li>Treat Perl types as objects</li> |
3365 | <li>Still uses <code>handles</code></li> |
3366 | <li>Pretend that native Perl types have methods</li> |
1c32806a |
3367 | </ul> |
3368 | </div> |
3369 | |
3370 | <div class="slide"> |
ba3e6f3b |
3371 | <h1>Native Delegation - Array(Ref)</h1> |
3372 | |
3373 | <ul> |
3374 | <li>Methods include: |
3375 | <ul> |
3376 | <li><code>push</code></li> |
3377 | <li><code>shift</code></li> |
3378 | <li><code>elements</code> - returns all elements</li> |
3379 | <li><code>count</code></li> |
3380 | <li><code>is_empty</code></li> |
3381 | <li>quite a few more</li> |
3382 | </ul> |
3383 | </li> |
3384 | </ul> |
c1d605db |
3385 | </div> |
ba3e6f3b |
3386 | |
3387 | <div class="slide"> |
3388 | <h1>Native Delegation - Array(Ref)</h1> |
1c32806a |
3389 | |
3390 | <pre><code>package Person; |
3391 | use Moose; |
1c32806a |
3392 | has _favorite_numbers => ( |
3393 | traits => [ 'Array' ], |
3394 | is => 'ro', |
3395 | isa => 'ArrayRef[Int]', |
3396 | default => sub { [] }, |
3397 | init_arg => undef, |
3398 | <span class="highlight">handles => |
3399 | { favorite_numbers => 'elements', |
3400 | add_favorite_number => 'push', |
3401 | },</span> |
3402 | );</code></pre> |
1c32806a |
3403 | </div> |
3404 | |
3405 | <div class="slide"> |
ba3e6f3b |
3406 | <h1>Native Delegation - Array(Ref)</h1> |
3407 | |
3408 | <pre><code>my $person = Person->new(); |
3409 | |
3410 | $person->add_favorite_number(7); |
3411 | $person->add_favorite_number(42); |
3412 | |
3413 | print "$_\n" |
3414 | for $person->favorite_numbers; |
3415 | |
3416 | # 7 |
3417 | # 42</code></pre> |
3418 | </div> |
3419 | |
3420 | <div class="slide"> |
3421 | <h1>Native Delegation</h1> |
1c32806a |
3422 | |
ba3e6f3b |
3423 | <ul> |
3424 | <li>Native types are ... |
3425 | <ul> |
3426 | <li>Number - <code>add</code>, <code>mul</code>, ...</li> |
3427 | <li>String - <code>append</code>, <code>chop</code>, ...</li> |
3428 | <li>Counter - <code>inc</code>, <code>dec</code>, ...</li> |
3429 | <li>Bool - <code>set</code>, <code>toggle</code>, ...</li> |
3430 | <li>Hash - <code>get</code>, <code>set</code>, ...</li> |
3431 | <li>Array - already saw it</li> |
78c5b76a |
3432 | <li>Code - <code>execute</code> and <code>execute_method</code></li> |
ba3e6f3b |
3433 | </ul> |
3434 | </li> |
3435 | </ul> |
3436 | </div> |
3437 | |
3438 | <div class="slide"> |
3439 | <h1>Curried Delegation</h1> |
3440 | |
3441 | <ul> |
3442 | <li>A delegation with some preset arguments</li> |
3443 | <li>Works with object or Native delegation</li> |
3444 | </ul> |
3445 | </div> |
3446 | |
3447 | <div class="slide"> |
3448 | <h1>Curried Delegation</h1> |
3449 | |
3450 | <pre><code>package Person; |
1c32806a |
3451 | use Moose; |
ba3e6f3b |
3452 | has account => ( |
3453 | is => 'ro', |
3454 | isa => 'BankAccount', |
3455 | handles => { |
3456 | receive_100 => |
3457 | <span class="highlight">[ 'deposit', 100 ]</span> |
3458 | give_100 => |
3459 | <span class="highlight">[ 'withdraw', 100 ]</span> |
c1d605db |
3460 | }, |
1c32806a |
3461 | );</code></pre> |
3462 | </div> |
3463 | |
1c32806a |
3464 | <div class="slide"> |
6f51d05c |
3465 | <h1>Curried Delegation</h1> |
3466 | |
3467 | <pre><code>$person->receive_100; |
3468 | # really is |
3469 | $person->account->deposit(100);</code></pre> |
3470 | </div> |
3471 | |
3472 | <div class="slide"> |
5d572684 |
3473 | <h1>Traits and Metaclasses</h1> |
3474 | |
3475 | <ul> |
3476 | <li>The ultimate in customization</li> |
3477 | <li>Per attribute metaclasses</li> |
3478 | <li>Per attribute roles applied to the attribute metaclass</li> |
3479 | <li>Change the meta-level behavior</li> |
3480 | </ul> |
3481 | </div> |
3482 | |
3483 | <div class="slide"> |
3484 | <h1>Traits and Metaclasses</h1> |
3485 | |
3486 | <ul> |
3487 | <li>The default metaclass is <code>Moose::Meta::Attribute</code></li> |
3488 | <li>Controls accessor generation, defaults, delegation, etc.</li> |
3489 | <li>Adding a role to this metaclass (or replacing it) allows for infinite customization</li> |
3490 | </ul> |
3491 | </div> |
3492 | |
3493 | <div class="slide"> |
3494 | <h1>Traits and Metaclasses</h1> |
3495 | |
3496 | <ul> |
78c5b76a |
3497 | <li>Can add/alter/remove an attribute parameter (from <code>has</code>)</li> |
5d572684 |
3498 | <li>Can change behavior of created attribute</li> |
3499 | </ul> |
3500 | </div> |
3501 | |
3502 | <div class="slide"> |
3503 | <h1>Simple Trait Example</h1> |
3504 | |
3505 | <pre><code>package Person; |
3506 | use Moose; |
3507 | use MooseX::LabeledAttributes; |
3508 | |
3509 | has ssn => ( |
3510 | <span class="highlight">traits => [ 'Labeled' ],</span> |
3511 | is => 'ro', |
3512 | isa => 'Str', |
3513 | <span class="highlight">label => 'Social Security Number',</span> |
3514 | ); |
5d572684 |
3515 | print <span class="highlight">Person->meta |
3516 | ->get_attribute('ssn')->label;</span></code></pre> |
3517 | </div> |
3518 | |
3519 | <div class="slide"> |
3520 | <h1>Simple Metaclass Example</h1> |
3521 | |
3522 | <pre><code>package Person; |
3523 | use Moose; |
3524 | use MooseX::LabeledAttributes; |
3525 | |
3526 | has ssn => ( |
3527 | <span class="highlight">metaclass => |
3528 | 'MooseX::Meta::Attribute::Labeled',</span> |
3529 | is => 'ro', |
3530 | isa => 'Str', |
3531 | <span class="highlight">label => 'Social Security Number',</span> |
3532 | ); |
5d572684 |
3533 | print <span class="highlight">Person->meta |
3534 | ->get_attribute('ssn')->label;</span></code></pre> |
3535 | </div> |
3536 | |
3537 | <div class="slide"> |
3538 | <h1>Traits vs Metaclass</h1> |
3539 | |
3540 | <ul> |
3541 | <li>Can apply any mix of traits to an attribute</li> |
3542 | <li>But just one metaclass</li> |
3543 | <li>Traits (aka roles) can cooperate</li> |
3544 | <li>Metaclasses require you to pick just one</li> |
3545 | </ul> |
3546 | </div> |
3547 | |
3548 | <div class="slide"> |
3549 | <h1>Advanced Attributes Summary</h1> |
3550 | |
3551 | <ul> |
3552 | <li>Use <code>weak_ref</code> to avoid circular references</li> |
3553 | <li>Use trigger to do an action post-attribute write</li> |
3554 | <li>Use delegations to hide "internal" objects</li> |
3555 | <li>Traits and metaclasses let you extend Moose's core attribute features</li> |
3556 | </ul> |
3557 | </div> |
3558 | |
9186987b |
3559 | <div class="slide"> |
3560 | <h1>Questions?</h1> |
3561 | </div> |
3562 | |
3563 | <div class="slide"> |
3564 | <h1>Exercises</h1> |
3565 | |
3566 | <pre># cd exercises |
debc93f8 |
3567 | # perl bin/prove -lv \ |
3568 | t/06-advanced-attributes.t |
9186987b |
3569 | |
3570 | Iterate til this passes all its tests</pre> |
3571 | </div> |
3572 | |
3573 | <div class="slide fake-slide0"> |
3574 | <h1>Part 7: Introspection</h1> |
3575 | </div> |
3576 | |
3577 | <div class="slide fake-slide0"> |
0066613d |
3578 | <h1>Part 8: A Brief Tour of MooseX</h1> |
9186987b |
3579 | </div> |
3580 | |
c1d605db |
3581 | <div class="slide"> |
6f51d05c |
3582 | <h1>Notable MX Modules on CPAN</h1> |
0066613d |
3583 | |
3584 | <ul> |
3585 | <li><strong>Not comprehensive</strong></li> |
78c5b76a |
3586 | <li>152 MooseX distributions on CPAN as of 02/02/2010</li> |
0066613d |
3587 | <li>Some of them are crap</li> |
3588 | </ul> |
3589 | </div> |
3590 | |
3591 | <div class="slide"> |
3592 | <h1>Already Mentioned Several</h1> |
3593 | |
3594 | <ul> |
255fe700 |
3595 | <li><code>MooseX::NonMoose</code> - best solution for subclassing non-Moose parents</li> |
3596 | <li><code>MooseX::Declare</code> - <em>real</em> Perl 5 OO</li> |
3597 | <li><code>MooseX::FollowPBP</code> and <code>MooseX::SemiAffordanceAccessor</code></li> |
3598 | <li><code>MooseX::Params::Validate</code> and <code>MooseX::Method::Signatures</code></li> |
3599 | <li><code>MooseX::Types</code></li> |
0066613d |
3600 | </ul> |
3601 | </div> |
3602 | |
3603 | <div class="slide"> |
3604 | <h1>MooseX::Declare</h1> |
3605 | |
3606 | <pre><code>use MooseX::Declare; |
3607 | use 5.10.0; # for say |
3608 | |
3609 | class Person { |
255fe700 |
3610 | has greeting => |
3611 | ( is => 'ro', isa => 'Str' ); |
0066613d |
3612 | |
3613 | method speak { |
3614 | say $self->greeting; |
3615 | } |
3616 | }</code></pre> |
3617 | </div> |
3618 | |
3619 | <div class="slide"> |
3620 | <h1>MooseX::Declare</h1> |
3621 | |
3622 | <ul> |
3623 | <li>Still experimental-ish, but seeing more and more use</li> |
3624 | <li><strong>Not</strong> a source filter!</li> |
3625 | <li>Hooks into the Perl parser rather than filtering all your code</li> |
255fe700 |
3626 | <li>But not supported by <code>PPI</code>, <code>perltidy</code>, etc.</li> (yet?) |
0066613d |
3627 | </ul> |
3628 | </div> |
3629 | |
3630 | <div class="slide"> |
3631 | <h1>MooseX::StrictConstructor</h1> |
3632 | |
3633 | <ul> |
255fe700 |
3634 | <li>By default, unknown constructor arguments are ignored</li> |
0066613d |
3635 | <li>MX::StrictConstructor turns these into an error</li> |
3636 | </ul> |
3637 | </div> |
3638 | |
3639 | <div class="slide"> |
3640 | <h1>MooseX::StrictConstructor</h1> |
3641 | |
3642 | <pre><code>package Person; |
3643 | |
3644 | use Moose; |
3645 | <span class="highlight">use MooseX::StrictConstructor;</span> |
3646 | |
3647 | has name => ( is => 'ro' ); |
3648 | |
3649 | Person->new |
3650 | ( na<span class="wrong">n</span>e => 'Ringo Shiina' ); # kaboom</code></pre> |
3651 | </div> |
3652 | |
3653 | <div class="slide"> |
3654 | <h1>MooseX::Traits</h1> |
3655 | |
3656 | <ul> |
3657 | <li>Combines object construction and role application</li> |
3658 | <li>Makes it easy to create one-off customized objects</li> |
3659 | </ul> |
3660 | </div> |
3661 | |
3662 | <div class="slide"> |
3663 | <h1>MooseX::Traits</h1> |
3664 | |
3665 | <pre><code>package MyApp::Thingy; |
3666 | use Moose; |
3667 | |
3668 | <span class="highlight">with 'MooseX::Traits';</span> |
3669 | |
3670 | my $thing = |
3671 | MyApp::Thingy-><span class="highlight">new_with_traits</span> |
3672 | ( <span class="highlight">traits => [ 'Foo', 'Bar' ],</span> |
3673 | size => 42 );</code></pre> |
3674 | </div> |
3675 | |
3676 | <div class="slide"> |
3677 | <h1>MooseX::Getopt</h1> |
3678 | |
3679 | <ul> |
3680 | <li>Makes command-line interface programs easy!</li> |
3681 | <li>Construct an object from CLI arguments</li> |
3682 | </ul> |
3683 | </div> |
3684 | |
3685 | <div class="slide"> |
3686 | <h1>MooseX::Getopt</h1> |
3687 | |
3688 | <pre><code>package App::CLI; |
3689 | use Moose; |
3690 | |
3691 | <span class="highlight">with 'MooseX::Getopt';</span> |
3692 | |
3693 | has file => |
3694 | ( is => 'ro', required => 1 ); |
3695 | has filters => |
78c5b76a |
3696 | ( is => 'ro', isa => 'ArrayRef[Str]' ); |
0066613d |
3697 | |
3698 | sub run { ... }</code></pre> |
3699 | </div> |
3700 | |
3701 | <div class="slide"> |
3702 | <h1>MooseX::Getopt</h1> |
3703 | |
3704 | <ul> |
3705 | <li>Then call it like this:</li> |
3706 | </ul> |
3707 | |
3708 | <pre><code>#!/usr/bin/perl |
3709 | |
3710 | use App::CLI; |
3711 | |
3712 | <span class="highlight">App::CLI->new_with_options()</span>->run();</code></pre> |
3713 | |
3714 | <pre>$ myapp-cli \ |
3715 | --file foo \ |
3716 | --filters compress \ |
3717 | --filters sanitize</pre> |
3718 | </div> |
3719 | |
3720 | <div class="slide"> |
3721 | <h1>MooseX::Clone</h1> |
3722 | |
3723 | <pre><code>package Person; |
3724 | |
3725 | use Moose; |
3726 | <span class="highlight">with 'MooseX::Clone';</span> |
3727 | |
3728 | my $person = Person->new; |
3729 | my $clone = <span class="highlight">$person->clone;</span></code></pre> |
3730 | </div> |
3731 | |
3732 | <div class="slide"> |
3733 | <h1>MooseX::NonMoose</h1> |
3734 | |
3735 | <ul> |
3736 | <li>Highly recommended for subclassing non-Moose parents</li> |
3737 | <li>Gets all the little annoying details right</li> |
3738 | </ul> |
3739 | </div> |
3740 | |
3741 | <div class="slide"> |
3742 | <h1>MooseX::Role::Parameterized</h1> |
3743 | |
3744 | <pre><code>package HasCollection; |
6f51d05c |
3745 | <span class="current incremental">use MooseX::Role::Parameterized;</span> |
3746 | <span class="incremental">parameter type => ( isa => 'Str', |
3747 | default => 'Item' );</span> |
3748 | <span class="incremental">role { |
0066613d |
3749 | my $p = shift; |
3750 | |
6f51d05c |
3751 | my $type = |
3752 | 'ArrayRef[' . $p->type() . ']'; |
0066613d |
3753 | has collection => |
3754 | ( is => 'ro', |
3755 | isa => $type ); |
6f51d05c |
3756 | };</span></code></pre> |
0066613d |
3757 | </div> |
3758 | |
3759 | <div class="slide"> |
3760 | <h1>MooseX::Role::Parameterized</h1> |
3761 | |
3762 | <pre><code>package Person; |
3763 | |
3764 | use Moose; |
3765 | with HasCollection => { type => 'Int' };</code></pre> |
3766 | </div> |
3767 | |
3768 | <div class="slide"> |
3769 | <h1>Questions?</h1> |
3770 | </div> |
3771 | |
9186987b |
3772 | <div class="slide fake-slide0"> |
3773 | <h1>Part 9: Writing Moose Extensions</h1> |
3774 | </div> |
3775 | |
8a719516 |
3776 | <div class="slide fake-slide0"> |
5e2eb691 |
3777 | <h1>The End</h1> |
8a719516 |
3778 | </div> |
3779 | |
3780 | <div class="slide"> |
3781 | <h1>More Information</h1> |
3782 | |
3783 | <ul> |
3784 | <li><a href="http://moose.perl.org/">http://moose.perl.org/</a></li> |
3785 | <li><a href="http://search.cpan.org/dist/Moose/lib/Moose/Manual.pod">Moose::Manual</a> and <a href="http://search.cpan.org/dist/Moose/lib/Moose/Cookbook.pod">Moose::Cookbook</a></li> |
3786 | <li><a href="irc://irc.perl.org/#moose">irc://irc.perl.org/#moose</a></li> |
3787 | <li>mailing list - <a href="mailto:moose@perl.org">moose@perl.org</a></li> |
3788 | <li>Slides and exercises are in Moose's git repo: |
3789 | <br /> |
78c5b76a |
3790 | <span style="font-size:80%; white-space: nowrap">git://jules.scsys.co.uk/gitmo/moose-presentations</span></li> |
8a719516 |
3791 | </ul> |
3792 | </div> |
3793 | |
55906a14 |
3794 | </div> |
b751d33f |
3795 | </body> |
3796 | </html> |
55906a14 |
3797 | |
3798 | <!-- |
3799 | |
3800 | Copyright 2009 David Rolsky. All Rights Reserved. |
3801 | |
3802 | This work is licensed under a Creative Commons Attribution-Share Alike |
3803 | 3.0 United States License See |
3804 | http://creativecommons.org/licenses/by-sa/3.0/us/ for details. |
3805 | |
3806 | --> |