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