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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"> |
217 | <h1>Before & After</h1> |
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> |
344 | <li>A quick bit of propoganda ...</li> |
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"> |
869 | <h1>extends</h1> |
870 | |
871 | <ul> |
872 | <li><code>extends</code> is sugar for declaring parent classes</li> |
873 | </ul> |
874 | |
875 | <pre><code>package Employee; |
876 | use Moose; |
877 | <span class="highlight">extends 'Person';</span></code></pre> |
878 | </div> |
879 | |
880 | <div class="slide"> |
881 | <h1>extends</h1> |
882 | |
883 | <ul> |
884 | <li>Each call to <code>extends</code> <strong>resets</strong> your parents</li> |
885 | </ul> |
886 | |
887 | <h2 class="wrong">WRONG</h2> |
888 | |
9b195048 |
889 | <pre><code>package EvilEmployee; |
b751d33f |
890 | use Moose; |
891 | extends 'Person'; |
55906a14 |
892 | extends 'Thief';</code></pre> |
b751d33f |
893 | |
894 | <h2 class="right">RIGHT</h2> |
895 | |
9b195048 |
896 | <pre><code>package EvilEmployee; |
b751d33f |
897 | use Moose; |
55906a14 |
898 | extends 'Person', 'Thief';</code></pre> |
b751d33f |
899 | </div> |
900 | |
901 | <div class="slide"> |
902 | <h1>Extending un-Moose-y Parents</h1> |
903 | |
904 | <pre><code>package My::LWP; |
905 | use Moose; |
55906a14 |
906 | extends 'LWP';</code></pre> |
b751d33f |
907 | |
908 | <ul> |
909 | <li>No <code>Moose::Object</code>, so ... |
910 | <ul> |
911 | <li>No attribute-handling <code>new()</code></li> |
912 | <li>No <code>BUILDARGS()</code> or <code>BUILD()</code></li> |
913 | <li>No <code>DEMOLISH()</code></li> |
914 | </ul> |
915 | </li> |
916 | <li>But see <code>MooseX::NonMoose</code> for a workaround</li> |
917 | </ul> |
918 | </div> |
919 | |
920 | <div class="slide"> |
9b195048 |
921 | <h1><code>overrides</code> and <code>super</code></h1> |
922 | |
923 | <ul> |
924 | <li><code>overrides</code> is another method modifier</li> |
925 | <li>An alternative to Perl's <code>SUPER::</code></li> |
926 | </ul> |
927 | </div> |
928 | |
929 | <div class="slide"> |
930 | <h1><code>overrides</code> and <code>super</code></h1> |
931 | |
932 | <pre><code>package Employee; |
933 | use Moose; |
934 | |
55906a14 |
935 | <span class="current">extends 'Person';</span> |
9b195048 |
936 | |
937 | <span class="incremental">overrides</span> work => sub { |
938 | my $self = shift; |
939 | |
940 | die "Pay me first" unless $self->got_paid; |
941 | <span class="incremental">super();</span> |
942 | }<span class="incremental">;</span></code></pre> |
55906a14 |
943 | </div> |
9b195048 |
944 | |
945 | <div class="slide"> |
946 | <h1>Caveat <code>super</code></h1> |
947 | |
948 | <ul> |
949 | <li>Mostly like <code>$self->SUPER::work(@_)</code></li> |
950 | <li><strong>But</strong> cannot change <code>@_</code>!</li> |
951 | <li>Binds the parent's method at compile time</li> |
952 | </ul> |
953 | </div> |
954 | |
955 | <div class="slide"> |
956 | <h1>Attributes (Part 1)</h1> |
957 | |
958 | <ul> |
959 | <li><code>has 'foo'</code></li> |
960 | <li>Use <code>is => 'ro'</code> or <code>is => 'rw'</code></li> |
961 | <li>Attributes without "is" have no accessors</li> |
962 | </ul> |
963 | </div> |
964 | |
965 | <div class="slide"> |
966 | <h1>Read-write attributes</h1> |
967 | |
968 | <pre><code>package Person; |
969 | use Moose; |
970 | |
55906a14 |
971 | has first_name => ( <span class="highlight">is => 'rw'</span> ); |
9b195048 |
972 | |
973 | my $person = |
974 | Person->new( first_name => 'Dave' ); |
975 | |
976 | $person->first_name('Stevan'); |
977 | print $person->first_name; # Stevan</code></pre> |
978 | |
979 | </div> |
980 | |
981 | <div class="slide"> |
982 | <h1>Read-only attributes</h1> |
983 | |
984 | <pre><code>package Person; |
985 | use Moose; |
986 | |
55906a14 |
987 | has first_name => ( <span class="highlight">is => 'ro'</span> ); |
9b195048 |
988 | |
989 | my $person = |
990 | Person->new( first_name => 'Dave' ); |
991 | |
992 | $person->first_name('Stevan'); |
993 | print $person->first_name; # Dave</code></pre> |
994 | |
995 | </div> |
996 | |
997 | <div class="slide"> |
998 | <h1>There is More to Come</h1> |
999 | |
1000 | <ul> |
1001 | <li>Attributes have a <em>lot</em> of features</li> |
1002 | </ul> |
1003 | </div> |
1004 | |
1005 | <div class="slide"> |
b751d33f |
1006 | <h1>Cleaning Up Moose Droppings</h1> |
1007 | |
1008 | <pre><code>package Person; |
1009 | use Moose; |
1010 | |
1011 | # true |
1012 | Person->can('extends');</code></pre> |
1013 | |
1014 | <ul> |
1015 | <li>Not very hygienic</li> |
1016 | </ul> |
1017 | </div> |
1018 | |
1019 | <div class="slide"> |
1020 | <h1>Cleaning Up Moose Droppings</h1> |
1021 | |
1022 | <pre><code>package Person; |
1023 | use Moose; |
1024 | |
1025 | ... |
1026 | |
1027 | no Moose; |
1028 | |
1029 | # false |
1030 | Person->can('extends');</code></pre> |
1031 | </div> |
1032 | |
1033 | <div class="slide"> |
1034 | <h1>No Moose</h1> |
1035 | |
1036 | <ul> |
1037 | <li><code>no Moose</code> at the end of a package is a best practice</li> |
1038 | <li>Just do it</li> |
1039 | </ul> |
1040 | </div> |
1041 | |
1042 | <div class="slide"> |
1043 | <h1>Immutability</h1> |
1044 | |
1045 | <ul> |
1046 | <li><span style="font-family: URW Chancery L; font-size: 140%">Stevan's Incantation of Fleet-Footedness</span></li> |
1047 | </ul> |
1048 | |
1049 | <pre><code>package Person; |
1050 | use Moose; |
1051 | |
1052 | <span class="highlight">__PACKAGE__->meta->make_immutable;</span></code></pre> |
1053 | </div> |
1054 | |
9b195048 |
1055 | <div class="slide"> |
1056 | <h1>What <code>make_immutable</code> does</h1> |
1057 | |
1058 | <ul> |
1059 | <li>Magic</li> |
1060 | <li>Uses <code>eval</code> to "inline" a constructor</li> |
1061 | <li>Memoizes a lot of meta-information</li> |
1062 | <li>Makes loading your class slower</li> |
1063 | <li>Makes object creation <em>much</em> faster</li> |
1064 | </ul> |
1065 | </div> |
1066 | |
1067 | <div class="slide"> |
1068 | <h1>When to Immutabilize?</h1> |
1069 | |
1070 | <ul> |
1071 | <li><em>Almost</em> always</li> |
1072 | <li>Startup time vs execution time</li> |
1073 | </ul> |
1074 | </div> |
1075 | |
ddd87d75 |
1076 | <div class="slide"> |
55906a14 |
1077 | <h1>Classes Summary</h1> |
1078 | |
1079 | <ul> |
1080 | <li><code>use Moose</code></li> |
1081 | <li><code>Class->meta</code></li> |
1082 | <li><code>Moose::Object</code> base class</li> |
1083 | <li><code>extends</code>, <code>overrides</code>, and <code>super</code></li> |
1084 | <li>Simple attributes: <code>has</code>, <code>is => 'ro'</code>, & <code>is => 'rw'</code></li> |
1085 | <li><code>no Moose</code></li> |
1086 | <li><code>__PACKAGE__->meta->make_immutable</code></li> |
1087 | </ul> |
1088 | </div> |
1089 | |
1090 | <div class="slide"> |
ba1c9923 |
1091 | <h1>Exercises</h1> |
ddd87d75 |
1092 | |
8d1ce1d7 |
1093 | <pre># cd exercises |
ba1c9923 |
1094 | $ perl bin/prove -lv t/00-prereq.t |
ddd87d75 |
1095 | |
1096 | Missing anything? Install it. (see tarballs/) |
1097 | |
ba1c9923 |
1098 | # perl bin/prove -lv t/01-classes.t |
1099 | |
55906a14 |
1100 | Iterate til this passes all its tests</pre> |
1101 | </div> |
1102 | |
1103 | <div class="slide fake-slide0"> |
1104 | <h1>Part 2: Roles</h1> |
1105 | </div> |
1106 | |
1107 | <div class="slide"> |
1108 | <h1>Just What Is a Role?</h1> |
1109 | |
1110 | <ul> |
1111 | <li>Mixin? Interface? Trait?</li> |
1112 | <li>Yes ... and more!</li> |
1113 | </ul> |
1114 | </div> |
1115 | |
1116 | <div class="slide"> |
1117 | <h1>Roles Can Have State <strong>and</strong> Behavior</h1> |
1118 | |
1119 | <pre><code>package HasPermissions; |
1120 | use Moose::Role; |
1121 | |
1122 | <span class="current"># state |
1123 | has access_level => ( is => 'rw' );</span> |
1124 | |
1125 | <span class="incremental"># behavior |
1126 | sub can_access { |
1127 | my $self = shift; |
1128 | my $required = shift; |
1129 | |
1130 | return $self->access_level >= $required; |
1131 | }</span></code></pre> |
1132 | |
1133 | </div> |
1134 | |
1135 | <div class="slide"> |
1136 | <h1>Roles Can Define Interfaces</h1> |
1137 | |
1138 | <pre><code>package Printable; |
1139 | use Moose::Role; |
1140 | |
1141 | requires 'as_string';</code></pre> |
1142 | </div> |
1143 | |
1144 | <div class="slide"> |
1145 | <h1>Roles Can Do All Three</h1> |
1146 | |
1147 | <pre><code>package Printable; |
1148 | use Moose::Role; |
1149 | |
1150 | requires 'as_string'; |
1151 | |
1152 | has has_been_printed => ( is => 'rw' ); |
1153 | |
1154 | sub print { |
1155 | my $self = shift; |
1156 | print $self->as_string; |
1157 | $self->has_been_printed(1); |
1158 | }</code></pre> |
1159 | </div> |
1160 | |
1161 | <div class="slide"> |
1162 | <h1>Classes Consume Roles</h1> |
1163 | |
1164 | <pre><code>package Person; |
1165 | use Moose; |
1166 | |
1167 | with 'HasPermissions';</code></pre> |
1168 | </div> |
1169 | |
1170 | <div class="slide"> |
1171 | <h1>Classes Consume Roles</h1> |
1172 | |
1173 | <pre><code>my $person = Person->new( |
1174 | first_name => 'Kenichi', |
1175 | last_name => 'Asai', |
1176 | access_level => 42, |
1177 | ); |
1178 | |
1179 | print $person->full_name |
1180 | . ' has ' |
1181 | . $person->can_access(42) |
1182 | ? 'great power' |
1183 | : 'little power';</code></pre> |
1184 | </div> |
1185 | |
1186 | <div class="slide"> |
1187 | <h1>Roles in Practice</h1> |
1188 | |
1189 | <ul> |
1190 | <li>Consuming a role =~ inlining the role</li> |
1191 | </ul> |
1192 | </div> |
1193 | |
1194 | <div class="slide"> |
1195 | <h1>In Other Words ...</h1> |
1196 | |
1197 | <pre><code>package Person; |
1198 | use Moose; |
1199 | |
1200 | <span class="highlight">with 'Printable';</span></code></pre> |
1201 | </div> |
1202 | |
1203 | <div class="slide"> |
1204 | <h1>In Other Words ...</h1> |
1205 | |
1206 | <pre><code>package Person; |
1207 | use Moose; |
1208 | |
1209 | <span class="delete">with 'Printable';</span> |
1210 | |
1211 | <span class="highlight">has has_been_printed => ( is => 'rw' ); |
1212 | |
1213 | sub print { |
1214 | my $self = shift; |
1215 | print $self->as_string; |
1216 | $self->has_been_printed(1); |
1217 | }</span></code></pre> |
1218 | </div> |
1219 | |
1220 | <div class="slide"> |
1221 | <h1>Except</h1> |
1222 | |
1223 | <ul> |
1224 | <li>Role consumption is introspectable</li> |
1225 | </ul> |
1226 | |
1227 | <pre><code>if ( Person->does('Printable') ) { ... } |
1228 | |
1229 | # or ... |
1230 | |
1231 | if ( Person->meta->does('Printable') ) { ... }</code></pre> |
1232 | |
1233 | </div> |
1234 | |
1235 | <div class="slide"> |
1236 | <h1>These Names Are the Same</h1> |
1237 | |
1238 | <ul> |
1239 | <li>What if a role and class define the same method?</li> |
1240 | <li>A class's <em>local</em> methods win over the role's</li> |
1241 | <li>The role's methods win over the class's <em>inherited</em> methods</li> |
1242 | </ul> |
1243 | </div> |
1244 | |
1245 | <div class="slide"> |
1246 | <h1>Conflicts Between Roles</h1> |
1247 | |
1248 | <ul> |
1249 | <li>Two roles with a method of the same name</li> |
1250 | <li>Generates a compile-time error when consumed by a class</li> |
1251 | </ul> |
1252 | </div> |
1253 | |
1254 | <div class="slide"> |
1255 | <h1>Conflict Example</h1> |
1256 | |
1257 | <pre><code>package IsFragile; |
1258 | use Moose::Role; |
1259 | |
1260 | sub break { ... } |
1261 | |
1262 | package CanBreakdance; |
1263 | use Moose::Role; |
1264 | |
1265 | sub break { ... }</code></pre> |
1266 | </div> |
1267 | |
1268 | <div class="slide"> |
1269 | <h1>Conflict Example</h1> |
1270 | |
1271 | <pre><code>package FragileDancer; |
1272 | use Moose; |
1273 | |
1274 | <span class="highlight">with 'IsFragile', 'CanBreakdance';</span></code></pre> |
1275 | |
1276 | <ul> |
1277 | <li>Only one <code>with</code>!</li> |
1278 | </ul> |
1279 | </div> |
1280 | |
1281 | <div class="slide"> |
1282 | <h1>Conflict Resolution</h1> |
1283 | |
1284 | <ul> |
1285 | <li>The consuming class must resolve the conflict by implementing th emethod</li> |
1286 | <li>Can use some combination of method exclusion and aliasing</li> |
1287 | </ul> |
1288 | </div> |
1289 | |
1290 | <div class="slide"> |
1291 | <h1>Method Aliasing</h1> |
1292 | |
1293 | <pre><code>package FragileDancer; |
1294 | use Moose; |
1295 | |
1296 | <span class="highlight">with 'IsFragile' => |
1297 | { alias => |
1298 | { break => 'break_bone' } }, |
1299 | 'CanBreakdance' => |
1300 | { alias => |
1301 | { break => 'break_it_down' } };</span></code></pre> |
1302 | |
1303 | <ul> |
1304 | <li>Renames the roles' methods</li> |
1305 | <li>Still conflicts, need to <code>exclude</code> as well</li> |
1306 | </ul> |
1307 | </div> |
1308 | |
1309 | <div class="slide"> |
1310 | <h1>Method Exclusion</h1> |
1311 | |
1312 | <pre><code>package FragileDancer; |
1313 | use Moose; |
1314 | |
1315 | <span class="highlight">with 'IsFragile' => |
1316 | { alias => |
1317 | { break => 'break_bone' }, |
1318 | exclude => 'break' }, |
1319 | 'CanBreakdance' => |
1320 | { alias => |
1321 | { break => 'break_dance' }, |
1322 | exclude => 'break' };</span></code></pre> |
1323 | </div> |
1324 | |
1325 | <div class="slide"> |
1326 | <h1>And then ...</h1> |
1327 | |
1328 | <pre><code>package FragileDancer; |
1329 | use Moose; |
ddd87d75 |
1330 | |
55906a14 |
1331 | sub break { |
1332 | my $self = shift; |
1333 | |
1334 | $self->break_dance; |
232c184d |
1335 | if ( rand(1) < 0.5 ) { |
55906a14 |
1336 | $self->break_bone; |
1337 | } |
1338 | }</code></pre> |
1339 | </div> |
1340 | |
1341 | <div class="slide"> |
1342 | <h1>Still Full of Fail</h1> |
1343 | |
1344 | <ul> |
1345 | <li>Roles are also about semantics!</li> |
1346 | <li>We've fulfilled the letter and lost the spirit</li> |
1347 | <li>Roles have a <em>meaning</em></li> |
1348 | <li>Think twice before blindly aliasing and excluding methods!</li> |
1349 | </ul> |
1350 | </div> |
1351 | |
1352 | <div class="slide"> |
1353 | <h1>Hot Role-on-Role Action</h1> |
1354 | |
1355 | <pre><code>package Comparable; |
1356 | use Moose::Role; |
1357 | |
1358 | requires 'compare';</code></pre> |
1359 | </div> |
1360 | |
1361 | <div class="slide"> |
1362 | <h1>Hot Role-on-Role Action</h1> |
1363 | |
1364 | <pre><code>package TestsEquality; |
1365 | use Moose::Role; |
1366 | |
1367 | with 'Comparable'; |
1368 | |
1369 | sub is_equal { |
1370 | my $self = shift; |
1371 | return $self->compare(@_) == 0; |
1372 | }</code></pre> |
1373 | </div> |
1374 | |
1375 | <div class="slide"> |
1376 | <h1>And then ...</h1> |
1377 | |
1378 | <pre><code>package Integer; |
1379 | use Moose; |
1380 | |
1381 | with 'TestsEquality'; |
1382 | |
1383 | # Satisfies the Comparable role |
1384 | sub compare { ... } |
1385 | |
1386 | Integer->does('TestsEquality'); # true |
1387 | Integer->does('Comparable'); # also true!</code></pre> |
1388 | </div> |
1389 | |
1390 | <div class="slide"> |
1391 | <h1>Name Conflicts Between Roles</h1> |
1392 | |
1393 | <pre><code>package HasSubProcess; |
1394 | use Moose::Role; |
1395 | |
1396 | <span class="highlight">sub execute { ... }</span> |
1397 | |
1398 | package Killer; |
1399 | use Moose::Role; |
1400 | |
1401 | with 'HasSubProcess'; |
1402 | |
1403 | <span class="highlight">sub execute { ... }</span></code></pre> |
1404 | </div> |
1405 | |
1406 | <div class="slide"> |
1407 | <h1>Delayed Conflict</h1> |
1408 | |
1409 | <pre><code>package StateOfTexas; |
1410 | with 'Killer';</code></pre> |
1411 | |
1412 | <ul> |
1413 | <li><code>StateOfTexas</code> must implement its own <code>execute</code></li> |
1414 | <li>But loading the <code>Killer</code> role by itself does not cause an error</li> |
1415 | </ul> |
1416 | </div> |
1417 | |
1418 | <div class="slide"> |
1419 | <h1>Roles as Interfaces</h1> |
1420 | |
1421 | <ul> |
1422 | <li>Roles can <code>require</code> methods of their consumers</li> |
1423 | <li>Compile-time checks</li> |
1424 | <li>Method must exist when the role is consumed</li> |
1425 | </ul> |
1426 | </div> |
1427 | |
1428 | <div class="slide"> |
1429 | <h1>The Attribute Gotcha</h1> |
1430 | |
1431 | <pre><code>package HasSize; |
1432 | use Moose::Role; |
1433 | |
1434 | <span class="current">requires 'size';</span> |
1435 | |
1436 | package Shirt; |
1437 | use Moose; |
1438 | |
1439 | <span class="incremental">with 'HasSize'; |
1440 | |
1441 | has size => ( is => 'ro' );</span></code></pre> |
1442 | </div> |
1443 | |
1444 | <div class="slide"> |
1445 | <h1>The Attribute Gotcha Workaround</h1> |
1446 | |
1447 | <pre><code>package HasSize; |
1448 | use Moose::Role; |
1449 | |
1450 | requires 'size'; |
1451 | |
1452 | package Shirt; |
1453 | use Moose; |
1454 | |
1455 | has size => ( is => 'ro' ); |
1456 | |
1457 | with 'HasSize';</code></pre> |
1458 | </div> |
1459 | |
1460 | <div class="slide"> |
1461 | <h1>Compile-time Is a Lie</h1> |
1462 | |
1463 | <ul> |
1464 | <li>Really, it's <em>package load</em> time</li> |
1465 | <li>That's run-time, but before the "real" run-time</li> |
1466 | <li>Moose does not rewire Perl, it's just sugar!</li> |
1467 | <li>(but <code>MooseX::Declare</code> <em>does</em> rewire Perl)</li> |
1468 | </ul> |
1469 | </div> |
1470 | |
1471 | <div class="slide"> |
1472 | <h1>Enforcing Roles</h1> |
1473 | |
1474 | <pre><code>package Comparison; |
1475 | use Moose; |
1476 | |
1477 | has [ 'left', 'right' ] => ( |
1478 | is => 'ro', |
1479 | <span class="highlight">does => 'Comparable',</span> |
1480 | ); |
1481 | </code></pre> |
1482 | |
1483 | <ul> |
1484 | <li>A sneak peek at type constraints</li> |
1485 | </ul> |
1486 | </div> |
1487 | |
1488 | |
1489 | <div class="slide"> |
1490 | <h1>Roles Can Be Applied to Objects</h1> |
1491 | |
1492 | <pre><code>use Moose::Util qw( apply_all_roles ); |
1493 | |
1494 | my $fragile_person = Person->new( ... ); |
1495 | apply_all_roles( $fragile_person, 'IsFragile' );</code></pre> |
1496 | |
1497 | <ul> |
1498 | <li>Does not change the <code>Person</code> class</li> |
1499 | <li>Works with non-Moose classes, great for monkey-patching!</li> |
1500 | </ul> |
1501 | </div> |
1502 | |
1503 | <div class="slide"> |
1504 | <h1>Roles Are Dirty Too</h1> |
1505 | |
1506 | <ul> |
1507 | <li>Once again, clean up those Moose droppings</li> |
1508 | </ul> |
1509 | |
1510 | <pre><code>package Comparable; |
1511 | use Moose::Role; |
1512 | |
1513 | requires 'compare'; |
1514 | |
1515 | <span class="highlight">no Moose::Role;</span></code></pre> |
1516 | |
1517 | <ul> |
1518 | <li>But roles cannot be made immutable</li> |
1519 | </ul> |
1520 | </div> |
1521 | |
1522 | <div class="slide"> |
1523 | <h1>The Zen of Roles</h1> |
1524 | |
1525 | <ul> |
1526 | <li>Roles represent discrete units of ... |
1527 | <ul> |
1528 | <li>state</li> |
1529 | <li>behavior</li> |
1530 | <li>interface</li> |
1531 | </ul> |
1532 | </li> |
1533 | <li>Roles are shareable between unrelated classes</li> |
1534 | <li>Roles are what a class <em>does</em>, not what it <em>is</em></li> |
1535 | <li>Roles <em>add</em> functionality, inheritance <em>specializes</em></li> |
1536 | </ul> |
1537 | </div> |
1538 | |
1539 | <div class="slide"> |
1540 | <h1>Abstract Examples</h1> |
1541 | |
1542 | <ul> |
1543 | <li>Human <em>@ISA</em> Animal</li> |
1544 | <li>Human <em>does</em> Toolmaker (as <em>does</em> Chimpanzee)</li> |
1545 | <li>Car <em>@ISA</em> Vehicle</li> |
1546 | <li>Car <em>does</em> HasEngine</li> |
1547 | </ul> |
1548 | </div> |
1549 | |
1550 | <div class="slide"> |
1551 | <h1>Real Examples</h1> |
1552 | |
1553 | <ul> |
1554 | <li>Objects representing SQL database components and queries |
1555 | <ul> |
1556 | <li>Schema, Table, Column, ColumnAlias</li> |
1557 | <li>Select, Insert, Update, Delete</li> |
1558 | </ul> |
1559 | </li> |
1560 | </ul> |
1561 | </div> |
1562 | |
1563 | <div class="slide"> |
1564 | <h1>Real Examples</h1> |
1565 | |
1566 | <ul> |
1567 | <li>Column and ColumnAlias both <em>do</em> ColumnLike</li> |
1568 | <li>ColumnLike things can be used in certain parts of queries</li> |
1569 | <li>All queries <em>do</em> HasWhereClause</li> |
1570 | <li>Select <em>does</em> Comparable and Selectable (for subselects)</li> |
1571 | <li>A where clause requires its components to <em>do</em> Comparable</li> |
1572 | </ul> |
1573 | </div> |
1574 | |
1575 | <div class="slide"> |
1576 | <h1>Exercises</h1> |
1577 | |
8d1ce1d7 |
1578 | <pre># cd exercises |
55906a14 |
1579 | # perl bin/prove -lv t/02-roles.t |
1580 | |
1581 | Iterate til this passes all its tests</pre> |
1582 | </div> |
1583 | |
8d1ce1d7 |
1584 | <div class="slide fake-slide0"> |
1585 | <h1>Part 3: Basic Attributes</h1> |
1586 | </div> |
1587 | |
1588 | <div class="slide"> |
1589 | <h1>Attributes Are Huge</h1> |
1590 | |
1591 | <ul> |
1592 | <li>Moose's biggest feature</li> |
1593 | <li>The target of <em>many</em> MooseX modules</li> |
1594 | </ul> |
1595 | </div> |
1596 | |
1597 | <div class="slide"> |
1598 | <h1>Quick Review</h1> |
1599 | |
1600 | <ul> |
1601 | <li>Declared with <code>has</code></li> |
1602 | <li>Read-only or read-write</li> |
1603 | </ul> |
1604 | |
1605 | <pre><code>package Shirt; |
1606 | use Moose; |
1607 | |
1608 | has 'color' => ( is => 'ro' ); |
1609 | has 'is_ripped' => ( is => 'rw' );</code></pre> |
1610 | </div> |
1611 | |
1612 | <div class="slide"> |
1613 | <h1>Required-ness</h1> |
1614 | |
1615 | <ul> |
1616 | <li>Required means "must be passed to the constructor"</li> |
1617 | <li>But can be <code>undef</code></li> |
1618 | </ul> |
1619 | </div> |
1620 | |
1621 | <div class="slide"> |
1622 | <h1>Required-ness</h1> |
1623 | |
1624 | <pre><code>package Person; |
1625 | use Moose; |
1626 | |
1627 | has first_name => ( |
1628 | is => 'ro', |
1629 | <span class="current">required => 1,</span> |
1630 | ); |
1631 | |
1632 | <span class="incremental">Person->new( first_name => undef ); # ok |
1633 | Person->new(); # kaboom</span></code></pre> |
1634 | </div> |
1635 | |
1636 | <div class="slide"> |
1637 | <h1>Default and Builder</h1> |
1638 | |
1639 | <ul> |
1640 | <li>Attributes can have defaults</li> |
1641 | <li>Simple non-referecne scalars (number, string)</li> |
1642 | <li>Subroutine reference</li> |
1643 | <li>A builder method</li> |
1644 | </ul> |
1645 | </div> |
1646 | |
1647 | <div class="slide"> |
1648 | <h1>Default</h1> |
1649 | |
1650 | <ul> |
1651 | <li>Can be a non-reference scalar (including <code>undef</code>)</li> |
1652 | </ul> |
1653 | |
1654 | <pre><code>package Person; |
1655 | use Moose; |
1656 | |
1657 | has bank => ( |
1658 | is => 'rw', |
1659 | default => 'Spire FCU', |
1660 | );</code></pre> |
1661 | </div> |
1662 | |
1663 | <div class="slide"> |
1664 | <h1>Default</h1> |
1665 | |
1666 | <ul> |
1667 | <li>Can be a subroutine reference</li> |
1668 | </ul> |
1669 | |
1670 | <pre><code>package Person; |
1671 | use Moose; |
1672 | |
1673 | has bank => ( |
1674 | is => 'rw', |
1675 | default => |
1676 | sub { Bank->new( |
1677 | name => 'Spire FCU' ) }, |
1678 | );</code></pre> |
1679 | </div> |
1680 | |
1681 | <div class="slide"> |
1682 | <h1>Default as a Subroutine Reference</h1> |
1683 | |
1684 | <ul> |
1685 | <li>Called as a method on the object</li> |
1686 | <li>Called anew for each object</li> |
1687 | </ul> |
1688 | </div> |
1689 | |
1690 | <div class="slide"> |
1691 | <h1>Why No Other Reference Types?</h1> |
1692 | |
1693 | <pre><code>package Person; |
1694 | use Moose; |
1695 | |
1696 | has bank => ( |
1697 | is => 'rw', |
1698 | <span class="wrong">default => Bank->new( |
1699 | name => 'Spire FCU' ),</span> |
1700 | );</code></pre> |
1701 | |
1702 | <ul> |
1703 | <li>Now <strong>every</strong> person shares the <strong>same</strong> Bank object!</li> |
1704 | </ul> |
1705 | </div> |
1706 | |
1707 | <div class="slide"> |
1708 | <h1>Defaulting to an Empty Reference</h1> |
1709 | |
1710 | <pre><code>package Person; |
1711 | use Moose; |
1712 | |
1713 | has packages => ( |
1714 | is => 'rw', |
1715 | default => <span class="highlight">sub { [] }</span>, |
1716 | );</code></pre> |
1717 | </div> |
1718 | |
1719 | <div class="slide"> |
1720 | <h1>What if I Want to Share?</h1> |
1721 | |
1722 | <pre><code>package Person; |
1723 | use Moose; |
1724 | |
1725 | my $highlander_bank = |
1726 | Bank->new( name => 'Spire FCU' ); |
1727 | |
1728 | has bank => ( |
1729 | is => 'rw', |
1730 | default => sub { $highlander_bank }, |
1731 | );</code></pre> |
1732 | </div> |
1733 | |
1734 | <div class="slide"> |
1735 | <h1>Builder</h1> |
1736 | |
1737 | <ul> |
1738 | <li>A method <em>name</em> which returns the default</li> |
1739 | </ul> |
1740 | </div> |
1741 | |
1742 | <div class="slide"> |
1743 | <h1>Builder</h1> |
1744 | |
1745 | <pre><code>package Person; |
1746 | use Moose; |
1747 | |
1748 | has bank => ( |
1749 | is => 'rw', |
1750 | builder => '_build_bank', |
1751 | ); |
1752 | |
1753 | sub _build_bank { |
1754 | my $self = shift; |
1755 | return Bank->new( name => 'Spire FCU' ); |
1756 | }</code></pre> |
1757 | </div> |
1758 | |
1759 | <div class="slide"> |
1760 | <h1>Default vs Builder</h1> |
1761 | |
1762 | <ul> |
1763 | <li>Use default for simple scalars</li> |
1764 | <li>Use default to return empty references</li> |
1765 | <li>Use default for <em>very</em> trivial subroutine references</li> |
1766 | <li>Use builder for everything else</li> |
1767 | </ul> |
1768 | </div> |
1769 | |
1770 | <div class="slide"> |
1771 | <h1>Builder Bonuses</h1> |
1772 | |
1773 | <ul> |
1774 | <li>Can be overridden and method modified, because it's called by <em>name</em></li> |
1775 | <li>Roles can require a builder</li> |
1776 | </ul> |
1777 | </div> |
1778 | |
1779 | <div class="slide"> |
1780 | <h1>Role Requires Builder</h1> |
1781 | |
1782 | <pre><code>package HasBank; |
1783 | use Moose::Role; |
1784 | |
1785 | requires '_build_bank'; |
1786 | |
1787 | has bank => ( |
1788 | is => 'ro', |
1789 | builder => '_build_bank', |
1790 | );</code></pre> |
1791 | </div> |
1792 | |
1793 | <div class="slide"> |
1794 | <h1>Lazy, Good for Nothing Attributes</h1> |
1795 | |
1796 | <ul> |
1797 | <li>Normally, defaults are generated during object construction</li> |
1798 | <li>This can be expensive</li> |
1799 | <li>We want to default to <code>$self->size * 2</code>, but attribute initialization order is unpredictable</li> |
1800 | <li>Use lazy attributes!</li> |
1801 | </ul> |
1802 | </div> |
1803 | |
1804 | <div class="slide"> |
1805 | <h1>The Power of Dynamic Defaults</h1> |
1806 | |
1807 | <pre><code>package Person; |
1808 | use Moose; |
1809 | |
1810 | has shoe_size => ( |
1811 | is => 'ro', |
1812 | );</code></pre> |
1813 | </div> |
1814 | |
1815 | <div class="slide"> |
1816 | <h1>The Power of Dynamic Defaults</h1> |
1817 | |
1818 | <pre><code>has shoes => ( |
1819 | is => 'ro', |
1820 | <span class="highlight">lazy => 1,</span> |
1821 | builder => '_build_shoes', |
1822 | ); |
1823 | |
1824 | sub _build_shoes { |
1825 | my $self = shift; |
1826 | |
1827 | return Shoes->new( |
1828 | size => <span class="highlight">$_[0]->shoe_size</span> ); |
1829 | }</code></pre> |
1830 | </div> |
1831 | |
1832 | <div class="slide"> |
1833 | <h1>Lazy is Good</h1> |
1834 | |
1835 | <ul> |
1836 | <li>Lazy defaults are executed when the attribute is read</li> |
1837 | <li>Can see other object attributes</li> |
1838 | <li>Still need to watch out for circular laziness</li> |
1839 | </ul> |
1840 | </div> |
1841 | |
1842 | <div class="slide"> |
1843 | <h1>Clearer and Predicate</h1> |
1844 | |
1845 | <ul> |
1846 | <li>Attributes can have a value, including <code>undef</code>, or not</li> |
1847 | <li>Can clear the value with a clearer method</li> |
1848 | <li>Can check for the existence of a value with a predicate method</li> |
1849 | <li>By default, these methods are not created</li> |
1850 | </ul> |
1851 | </div> |
1852 | |
1853 | <div class="slide"> |
1854 | <h1>Clearer and Predicate</h1> |
1855 | |
1856 | <pre><code>package Person; |
1857 | use Moose; |
1858 | |
1859 | has account => ( |
1860 | is => 'ro', |
1861 | lazy => 1, |
1862 | builder => '_build_account', |
1863 | <span class="highlight">clearer => '_clear_account', |
1864 | predicate => 'has_account',</span> |
1865 | );</code></pre> |
1866 | </div> |
1867 | |
1868 | <div class="slide"> |
1869 | <h1>Clearer and Lazy Defaults</h1> |
1870 | |
1871 | <ul> |
1872 | <li>Lazy defaults are good for computed attributes</li> |
1873 | <li>Clear the attribute when the source data changes</li> |
1874 | <li>Recalculated at next access</li> |
1875 | </ul> |
1876 | </div> |
1877 | |
1878 | <div class="slide"> |
1879 | <h1>Renaming constructor arguments</h1> |
1880 | |
1881 | <ul> |
1882 | <li>By default, constructor names = attribute names</li> |
1883 | <li>Use <code>init_arg</code> to change this</li> |
1884 | <li>Set <code>init_arg => undef</code> to make it unconstructable</li> |
1885 | </ul> |
1886 | </div> |
1887 | |
1888 | <div class="slide"> |
1889 | <h1>Some <code>init_arg</code> examples</h1> |
1890 | |
1891 | <pre><code>package Person; |
1892 | use Moose; |
1893 | |
1894 | has shoe_size => ( |
1895 | is => 'ro', |
1896 | <span class="highlight">init_arg => 'foot_size',</span> |
1897 | ); |
1898 | |
1899 | Person->new( <span class="wrong">shoe_size => 13</span> ); |
1900 | |
1901 | my $person = |
1902 | Person->new( <span class="right">foot_size => 13</span> ); |
1903 | print $person->shoe_size;</code></pre> |
1904 | </div> |
1905 | |
1906 | <div class="slide"> |
1907 | <h1>Some <code>init_arg</code> examples</h1> |
1908 | |
1909 | <pre><code>package Person; |
1910 | use Moose; |
1911 | |
1912 | has shoes => ( |
1913 | is => 'ro', |
1914 | <span class="highlight">init_arg => undef,</span> |
1915 | ); |
1916 | |
1917 | Person->new( <span class="wrong">shoes => Shoes->new</span> );</code></pre> |
1918 | </div> |
1919 | |
1920 | <div class="slide"> |
1921 | <h1>Why Set <code>init_arg => undef</code>?</h1> |
1922 | |
1923 | <ul> |
1924 | <li>Use this with a lazy default for attributes-as-cache</li> |
1925 | <li>Compute the value as needed</li> |
1926 | <li>Ensure that it is always generated correctly (not set by constructor)</li> |
1927 | <li>Use triggers or method modifiers (coming soon) to clear the value</li> |
1928 | </ul> |
1929 | </div> |
1930 | |
1931 | <div class="slide"> |
1932 | <h1>Attribute Inheritance</h1> |
1933 | |
1934 | <ul> |
1935 | <li>By default, subclasses inherit attribute as-is</li> |
1936 | <li>Can change some attribute parameters in subclasses |
1937 | <ul> |
1938 | <li>default</li> |
1939 | <li>builder</li> |
1940 | <li>required</li> |
1941 | <li>lazy</li> |
1942 | <li>others we've not yet covered</li> |
1943 | </ul> |
1944 | </li> |
1945 | </ul> |
1946 | </div> |
1947 | |
1948 | <div class="slide"> |
1949 | <h1>Attribute Inheritance Example</h1> |
1950 | |
1951 | <pre><code>package Employee; |
1952 | use Moose; |
1953 | |
1954 | extends 'Person'; |
1955 | |
1956 | has '<span class="highlight">+first_name</span>' => ( |
1957 | default => 'Joe', |
1958 | );</code></pre> |
1959 | </div> |
1960 | |
1961 | <div class="slide"> |
1962 | <h1>Attribute Inheritance Warning</h1> |
1963 | |
1964 | <ul> |
1965 | <li>An attribute is a contract about a class's API</li> |
1966 | <li>Don't break that contract in a subclass</li> |
1967 | <li>Especially important in the context of types</li> |
1968 | </ul> |
1969 | </div> |
1970 | |
1971 | <div class="slide"> |
1972 | <h1>Changing Accessor Names</h1> |
1973 | |
1974 | <pre><code>package Person; |
1975 | use Moose; |
1976 | |
1977 | has first_name => ( |
1978 | <span class="highlight">reader</span> => 'first_name', |
1979 | <span class="highlight">writer</span> => 'first_name', |
1980 | );</code></pre> |
1981 | |
1982 | <ul> |
1983 | <li>The long-hand version of <code>is => 'rw'</code></li> |
1984 | </ul> |
1985 | </div> |
1986 | |
1987 | <div class="slide"> |
1988 | <h1>Changing Accessor Names</h1> |
1989 | |
1990 | <pre><code>package Person; |
1991 | use Moose; |
1992 | |
1993 | has first_name => ( |
1994 | <span class="highlight">reader</span> => 'first_name', |
1995 | <span class="highlight">writer</span> => undef, |
1996 | );</code></pre> |
1997 | |
1998 | <ul> |
1999 | <li>The long-hand version of <code>is => 'ro'</code></li> |
2000 | </ul> |
2001 | </div> |
2002 | |
2003 | |
2004 | <div class="slide"> |
2005 | <h1>Changing Accessor Names</h1> |
2006 | |
2007 | <pre><code>package Person; |
2008 | use Moose; |
2009 | |
2010 | has first_name => ( |
2011 | <span class="highlight">reader</span> => 'get_first_name', |
2012 | <span class="highlight">writer</span> => 'set_first_name, |
2013 | );</code></pre> |
2014 | </div> |
2015 | |
2016 | <div class="slide"> |
2017 | <h1>Changing Accessor Names</h1> |
2018 | |
2019 | <pre><code>package Person; |
2020 | use Moose; |
2021 | |
2022 | has first_name => ( |
2023 | <span class="highlight">is</span> => 'rw', |
2024 | <span class="highlight">writer</span> => '_first_name', |
2025 | );</code></pre> |
2026 | |
2027 | <ul> |
2028 | <li>Can also mix-and-match</li> |
2029 | </ul> |
2030 | </div> |
2031 | |
2032 | <div class="slide"> |
2033 | <h1>ETOOMUCHTYPING</h1> |
2034 | |
2035 | <ul> |
2036 | <li><code>MooseX::FollowPBP</code><br /><code>get_foo</code> and <code>set_foo</code></li> |
2037 | <li><code>MooseX::SemiAffordanceAccessor</code><br /><code>foo</code> and <code>set_foo</code></li> |
2038 | </ul> |
2039 | </div> |
2040 | |
2041 | <div class="slide"> |
2042 | <h1>ETOOMUCHTYPING</h1> |
2043 | |
2044 | <pre><code>package Person; |
2045 | use Moose; |
2046 | <span class="highlight">use MooseX::SemiAffordanceAccessor;</span> |
2047 | |
2048 | has first_name => ( |
2049 | is => 'rw', |
2050 | );</code></pre> |
2051 | |
2052 | <ul> |
2053 | <li>Creates <code>first_name</code> and <code>set_first_name</code></li> |
2054 | </ul> |
2055 | </div> |
2056 | |
2057 | <div class="slide"> |
2058 | <h1>Exercises</h1> |
2059 | |
2060 | <pre># cd exercises |
2061 | # perl bin/prove -lv t/03-basic-attributes.t |
2062 | |
2063 | Iterate til this passes all its tests</pre> |
2064 | </div> |
2065 | |
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2066 | </div> |
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2067 | </body> |
2068 | </html> |
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2069 | |
2070 | <!-- |
2071 | |
2072 | Copyright 2009 David Rolsky. All Rights Reserved. |
2073 | |
2074 | This work is licensed under a Creative Commons Attribution-Share Alike |
2075 | 3.0 United States License See |
2076 | http://creativecommons.org/licenses/by-sa/3.0/us/ for details. |
2077 | |
2078 | --> |
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