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+ <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>.
+ </div>
+
<h2>Introduction to Moose</h2>
</div>
</div>
<div class="slide">
<h1>Introduction to Moose</h1>
- <h2>YAPC 2009</h2>
+ <h2>Dave Rolsky</h2>
+</div>
+
+<div class="slide">
+ <h1>Introduce Yourselves</h1>
+
+ <ul>
+ <li>Your name</li>
+ <li>What you do with Perl</li>
+ <li>Why you're here today (optional)</li>
+ </ul>
</div>
<div class="slide">
<ul>
<li><strong>Declarative</strong> OO sugar</li>
<li>Introspectable</li>
- <li>Extensible</li>
+ <li>Extensible (202 MooseX::* on CPAN)</li>
+ <li>Community approved (1200+ downstream dependents on CPAN)</li>
</ul>
</div>
<div class="slide">
- <h1>Concepts</h1>
+ <h1>Moose Background</h1>
<ul>
+ <li>Created by Stevan Little, first released in 2006</li>
<li>Moose builds on Perl 5's native OO</li>
<li>Borrows ideas from other languages, notably Perl 6</li>
<li>Provides semantics for common operations</li>
</ul>
</div>
+<div class="slide fake-slide0">
+ <h1>Part 0: Moose Concepts</h1>
+</div>
+
<div class="slide">
<h1>Classes</h1>
<li>
Attributes have ...
<ul>
- <li>Access-control (read-only vs read-write)</li>
+ <li>Mutability (read-only vs read-write)</li>
<li>An optional type</li>
<li>Accessor methods</li>
<li>Delegation methods</li>
<pre><code>package Person;
use Moose;
-<span class="highlight">has 'first_name' => ( is => 'rw' );</span></code></pre>
+<span class="highlight">has first_name => ( is => 'ro' );</span></code></pre>
</div>
<ul>
<li>AKA advice</li>
<li>"<strong>Before</strong> foo(), do this first"</li>
- <li>"Do this <strong>after</strong> foo()</li>
+ <li>"Do this <strong>after</strong> foo()"</li>
<li>"Put this code <strong>around</strong> foo()"</li>
</ul>
</div>
<div class="slide">
- <h1>Before & After</h1>
+ <h1>Before and After</h1>
<pre><code>before 'foo'
=> sub { warn 'About to call foo()' };
my @return =
$self->$real_foo( @_, bar => 42 );
- return ( @return, 'modify return values' );
+ return (
+ @return,
+ 'modify return values'
+ );
};</code></pre>
</div>
<pre><code>package Person;
use Moose;
-has 'weight' => ( is => 'ro', <span class="highlight">isa => 'Int'</span> );
+has weight => (
+ is => 'ro',
+ <span class="highlight">isa => 'Int'</span>,
+);
# kaboom
-Person->new( weight => 'fat' );</code></pre>
+Person->new( weight => 'heavy' );</code></pre>
</div>
<div class="slide">
<pre><code>package Person;
use Moose;
-has 'blog_uri' => (
+has blog_uri => (
is => 'rw',
isa => 'URI',
- <span class="highlight">handles => { 'blog_hostname' => 'host' },</span>
+ <span class="highlight">handles => { 'blog_host' => 'host' },</span>
);
-<span class="highlight">$person->blog_hostname;</span>
-# really calls $person->blog_uri->host
+<span class="highlight">$person->blog_host;</span>
+# really calls $person->blog_uri->host</code></pre>
</div>
<div class="slide">
<h1>Why Moose?</h1>
<ul>
- <li>A quick bit of propoganda ...</li>
+ <li>A quick bit of propaganda ...</li>
</ul>
</div>
<div class="slide">
<h1>Typo?</h1>
- <code>$self->{last_na<span class="highlight">n</span>e}</code>
+ <code>$self->{last_na<span class="wrong">n</span>e}</code>
</div>
<div class="slide">
);</code></pre>
</div>
+<div class="slide">
+ <h1>More Why Moose?</h1>
+
+ <ul>
+ <li>Less code == fewer bugs</li>
+ <li>Moose is well-tested, test your own code, not Moose</li>
+ <li>Focus on <strong>what</strong>, not <strong>how</strong></li>
+ </ul>
+</div>
+
<div class="slide fake-slide0">
- <h1>Moose Classes</h1>
+ <h1>Part 1: Moose Classes</h1>
</div>
<div class="slide">
</div>
<div class="slide">
+ <h1>BUILDARGS</h1>
+
+ <ul>
+ <li>Processes <code>new</code>'s <code>@_</code>, returns a hash reference of attribute name/value pairs</li>
+ <li>Accepts a hash or hashref; errors otherwise</li>
+ <li>Provide your own for other cases</li>
+ <li><strong>Always</strong> call <code>$class->SUPER::BUILDARGS(@_)</code> as a fallback!</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>BUILDARGS Example</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+sub BUILDARGS {
+ my $class = shift;
+
+ if ( @_ == 1 && ! ref $_[0] ) {
+ <span class="highlight">return { ssn => $_[0] };</span>
+ }
+ <span class="highlight">return $class->SUPER::BUILDARGS(@_)</span>;
+}
+
+<span class="highlight">Person->new('123-45-6789')</span></code></pre>
+</div>
+
+<div class="slide">
+ <h1>BUILD</h1>
+
+ <ul>
+ <li>Called after object is created, before <code>new</code> returns</li>
+ <li>Chance to do more complex validation, set complex attributes</li>
+ <li>Called in reverse inheritance order, parents to children</li>
+ <li>Return value is ignored</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>BUILD Example</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+sub BUILD {
+ my $self = shift;
+
+ if ( $self->country_of_residence
+ eq 'USA' ) {
+ die 'All US residents'
+ . ' must have an SSN'
+ unless $self->has_ssn;
+ }
+}</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Object Construction a la Moose</h1>
+
+ <pre><code>Person->new(@args)</code></pre>
+
+ <ol style="margin-top: 0">
+ <li>Calls <code>Person->BUILDARGS(@args)</code> to turn <code>@args</code> into a hashref</li>
+ <li>Blesses a reference</li>
+ <li>Populates attributes based on the hashref from #1</li>
+ <li>Calls <code>$new_object->BUILDALL($constructor_args)</code>
+ <br />... which calls all <code>BUILD</code> methods</li>
+ <li>Returns the object</li>
+ </ol>
+</div>
+
+<div class="slide">
+ <h1>The Object is Opaque</h1>
+
+ <ul>
+ <li>Technically it's a hash reference</li>
+ <li><span class="wrong">If you <em>ever</em> treat it as one <strong>you are doing it wrong!</strong></span></li>
+ <li>Moose probably provides a feature to do what you need</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>DEMOLISH</h1>
+
+ <ul>
+ <li>Like <code>DESTROY</code>, but Moose makes sure all <code>DEMOLISH</code> methods in a hierarchy are called</li>
+ <li>Called in normal inheritance order, children to parents</li>
+ <li><em>Never</em> called by you, only by Perl itself</li>
+ </ul>
+</div>
+
+<div class="slide">
<h1>extends</h1>
<ul>
<li><code>extends</code> is sugar for declaring parent classes</li>
+ <li>Also ensures metaclass compatibility between parent and child</li>
+ <li>Do not <code>use base</code></li>
</ul>
<pre><code>package Employee;
<li>Each call to <code>extends</code> <strong>resets</strong> your parents</li>
</ul>
- <h2 class="wrong">WRONG</h2>
+ <h2 class="wrong">Wrong</h2>
<pre><code>package EvilEmployee;
use Moose;
extends 'Person';
-extends 'Thief';</pre></code>
+extends 'Thief';</code></pre>
- <h2 class="right">RIGHT</h2>
+ <h2 class="right">Right</h2>
<pre><code>package EvilEmployee;
use Moose;
-extends 'Person', 'Thief';</pre></code>
+extends 'Person', 'Thief';</code></pre>
</div>
<div class="slide">
<pre><code>package My::LWP;
use Moose;
-extends 'LWP';</pre></code>
+extends 'LWP';</code></pre>
<ul>
<li>No <code>Moose::Object</code>, so ...
<li>No <code>DEMOLISH()</code></li>
</ul>
</li>
- <li>But see <code>MooseX::NonMoose</code> for a workaround</li>
+ <li>But <code>MooseX::NonMoose</code> fixes all of this</li>
</ul>
</div>
<div class="slide">
- <h1><code>overrides</code> and <code>super</code></h1>
+ <h1><code>override</code> and <code>super</code></h1>
<ul>
- <li><code>overrides</code> is another method modifier</li>
+ <li><code>override</code> is another method modifier</li>
<li>An alternative to Perl's <code>SUPER::</code></li>
+ <li><em>Declares</em> your intent to override a method</li>
</ul>
</div>
<div class="slide">
- <h1><code>overrides</code> and <code>super</code></h1>
+ <h1><code>override</code> and <code>super</code></h1>
<pre><code>package Employee;
use Moose;
-<span class="incremental current">extends 'Person';</span>
+<span class="current incremental">extends 'Person';</span>
-<span class="incremental">overrides</span> work => sub {
+<span class="incremental">override</span> <span class="incremental">work</span> <span class="incremental">=> sub {
my $self = shift;
- die "Pay me first" unless $self->got_paid;
- <span class="incremental">super();</span>
-}<span class="incremental">;</span></code></pre>
+ die "Pay me first"
+ unless $self->got_paid;
+ super();
+}</span><span class="incremental">;</span></code></pre>
+</div>
<div class="slide">
<h1>Caveat <code>super</code></h1>
<ul>
<li>Mostly like <code>$self->SUPER::work(@_)</code></li>
<li><strong>But</strong> cannot change <code>@_</code>!</li>
- <li>Binds the parent's method at compile time</li>
+ <li>Binds the parent's method <strong>correctly</strong> at compile time</li>
+ <li>Parent determined by checking <code>Child->meta()->superclasses()</code></li>
</ul>
</div>
<div class="slide">
- <h1>Attributes (Part 1)</h1>
+ <h1>Minimal Attributes</h1>
<ul>
<li><code>has 'foo'</code></li>
<pre><code>package Person;
use Moose;
-has 'first_name' => ( <span class="highlight">is => 'rw'</span> );
+has first_name => ( <span class="highlight">is => 'rw'</span> );
my $person =
Person->new( first_name => 'Dave' );
<pre><code>package Person;
use Moose;
-has 'first_name' => ( <span class="highlight">is => 'ro'</span> );
+has first_name => ( <span class="highlight">is => 'ro'</span> );
my $person =
Person->new( first_name => 'Dave' );
-$person->first_name('Stevan');
-print $person->first_name; # Dave</code></pre>
+$person->first_name('Stevan'); # dies</code></pre>
</div>
use Moose;
# true
-Person->can('extends');</code></pre>
+Person->can('extends');</code></pre>
<ul>
<li>Not very hygienic</li>
...
-no Moose;
+<span class="highlight">no Moose;</span>
+
+# false
+Person->can('extends');</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Cleaning Up Moose Droppings</h1>
+
+ <pre><code>package Person;
+use Moose;
+<span class="highlight">use namespace::autoclean;</span>
+
+...
# false
-Person->can('extends');</code></pre>
+Person->can('extends');</code></pre>
</div>
<div class="slide">
<h1>No Moose</h1>
<ul>
- <li><code>no Moose</code> at the end of a package is a best practice</li>
+ <li>Cleaning up is a best practice</li>
+ <li>Say <code>no Moose</code> at the end of a package</li>
+ <li>Or <code>use namespace::autoclean</code> at the top</li>
<li>Just do it</li>
</ul>
</div>
<h1>Immutability</h1>
<ul>
- <li><span style="font-family: URW Chancery L; font-size: 140%">Stevan's Incantation of Fleet-Footedness</span></li>
+ <li><span style="font-family: URW Chancery L; font-size: 120%">Stevan's Incantation of Fleet-Footedness</span></li>
</ul>
<pre><code>package Person;
use Moose;
-<span class="highlight">__PACKAGE__->meta->make_immutable;</span></code></pre>
+<span class="highlight">__PACKAGE__->meta->make_immutable;</span></code></pre>
</div>
<div class="slide">
</div>
<div class="slide">
- <h1>Classes - Exercises</h1>
+ <h1>Classes Summary</h1>
- <pre>$ cd exercises
-$ prove -lv t/00-prereq.t
+ <ul>
+ <li><code>use Moose</code></li>
+ <li><code>Class->meta</code></li>
+ <li><code>Moose::Object</code> base class</li>
+ <li><code>extends</code>, <code>override</code>, and <code>super</code></li>
+ <li>Simple attributes: <code>has</code>, <code>is => 'ro'</code>, & <code>is => 'rw'</code></li>
+ <li><code>no Moose</code></li>
+ <li><code>__PACKAGE__->meta->make_immutable</code></li>
+ </ul>
+</div>
-Missing anything? Install it. (see tarballs/)
+<div class="slide">
+ <h1>Questions?</h1>
+</div>
-# prove -lv t/01-classes.t
-#
+<div class="slide">
+ <h1>Exercises</h1>
-</body>
-</html>
+ <pre># cd exercises
+
+# perl bin/prove -lv t/00-prereq.t
+
+## Read the instructions in t/01-classes.t
+
+# perl bin/prove -lv t/01-classes.t
+
+# edit lib/Person.pm and lib/Employee.pm
+
+Iterate til this passes all its tests</pre>
+</div>
+
+<div class="slide fake-slide0">
+ <h1>Part 2: Roles</h1>
+</div>
+
+<div class="slide">
+ <h1>Just What Is a Role?</h1>
+
+ <ul>
+ <li>Mixin? Interface? Trait?</li>
+ <li>Yes ... and more!</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Roles - State <strong>and</strong> Behavior</h1>
+
+ <pre><code>package HasPermissions;
+use Moose::Role;
+<span class="current incremental"># state
+has access_level => ( is => 'rw' );</span>
+
+<span class="incremental"># behavior
+sub can_access {
+ my $self = shift;
+ my $required = shift;
+
+ return $self->access_level
+ >= $required;
+}</span></code></pre>
+
+</div>
+
+<div class="slide">
+ <h1>Roles Can Define Interfaces</h1>
+
+ <pre><code>package Printable;
+use Moose::Role;
+
+requires 'as_string';</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Roles Can Do All Three</h1>
+
+ <pre><code>package Printable;
+use Moose::Role;
+
+requires 'as_string';
+
+has has_been_printed => ( is => 'rw' );
+
+sub print {
+ my $self = shift;
+ print $self->as_string;
+ $self->has_been_printed(1);
+}</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Classes Consume Roles</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+with 'Printable';</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Classes Consume Roles</h1>
+
+<pre><code>package Person;
+
+sub as_string { $_[0]->first_name() }
+
+...
+
+my $person = Person->new(
+ first_name => 'Kenichi',
+ last_name => 'Asai',
+ access_level => 42,
+);
+
+$person->print();</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Roles in Practice</h1>
+
+ <ul>
+ <li>Consuming a role =~ inlining the role</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>In Other Words ...</h1>
+
+<pre><code>package Person;
+use Moose;
+
+<span class="highlight">with 'Printable';</span>
+
+sub as_string { $_[0]->first_name() }</code></pre>
+</div>
+
+<div class="slide">
+ <h1>In Other Words ...</h1>
+
+<pre><code>package Person;
+use Moose;
+
+<span class="delete">with 'Printable';</span>
+
+sub as_string { $_[0]->first_name() }
+
+<span class="highlight">has has_been_printed => ( is => 'rw' );
+
+sub print {
+ my $self = shift;
+ print $self->as_string;
+ $self->has_been_printed(1);
+}</span></code></pre>
+</div>
+
+<div class="slide">
+ <h1>Except</h1>
+
+ <ul>
+ <li>Role consumption is introspectable</li>
+ </ul>
+
+ <pre><code>if ( Person->does('Printable') ) { ... }
+
+# or ...
+
+Person->meta->does_role('Printable')</code></pre>
+
+</div>
+
+<div class="slide">
+ <h1>These Names Are the Same</h1>
+
+ <ul>
+ <li>What if a role and class define the same method?</li>
+ <li>A class's <em>local</em> methods win over the role's</li>
+ <li>The role's methods win over the class's <em>inherited</em> methods</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Conflicts Between Roles</h1>
+
+ <ul>
+ <li>Two roles with a method of the same name</li>
+ <li>Generates a compile-time error when consumed by a class</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Conflict Example</h1>
+
+ <pre><code>package IsFragile;
+use Moose::Role;
+
+sub break { ... }
+
+package CanBreakdance;
+use Moose::Role;
+
+sub break { ... }</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Conflict Example</h1>
+
+ <pre><code>package FragileDancer;
+use Moose;
+
+<span class="highlight">with 'IsFragile', 'CanBreakdance';</span></code></pre>
+
+ <ul>
+ <li>Only one <code>with</code>!</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Conflict Resolution</h1>
+
+ <ul>
+ <li>The consuming class must resolve the conflict by implementing the method</li>
+ <li>Can use some combination of method exclusion and aliasing</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Conflicts Are a Smell</h1>
+
+ <ul>
+ <li>Roles are about semantics!</li>
+ <li>Roles have a <em>meaning</em></li>
+ <li>Method name conflicts smell like bad design</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Roles With Roles</h1>
+
+ <pre><code>package Comparable;
+use Moose::Role;
+
+requires 'compare';</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Roles With Roles</h1>
+
+ <pre><code>package TestsEquality;
+use Moose::Role;
+
+with 'Comparable';
+
+sub is_equal {
+ my $self = shift;
+ return $self->compare(@_) == 0;
+}</code></pre>
+</div>
+
+<div class="slide">
+ <h1>And then ...</h1>
+
+ <pre><code>package Integer;
+use Moose;
+
+with 'TestsEquality';
+
+# Satisfies the Comparable role
+sub compare { ... }
+
+Integer->does('TestsEquality'); # true
+Integer->does('Comparable'); # also true!</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Roles as Interfaces</h1>
+
+ <ul>
+ <li>Roles can <code>require</code> methods of their consumers</li>
+ <li>Compile-time checks</li>
+ <li>Method must exist when the role is consumed</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>The Attribute Gotcha</h1>
+
+<pre><code>package HasSize;
+use Moose::Role;
+
+<span class="current incremental">requires 'size';</span>
+
+package Shirt;
+use Moose;
+
+<span class="incremental">with 'HasSize';
+
+has size => ( is => 'ro' );</span></code></pre>
+</div>
+
+<div class="slide">
+ <h1>The Attribute Gotcha Workaround</h1>
+
+ <pre><code>package HasSize;
+use Moose::Role;
+
+requires 'size';
+
+package Shirt;
+use Moose;
+
+has size => ( is => 'ro' );
+
+with 'HasSize';</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Compile-time Is a Lie</h1>
+
+ <ul>
+ <li>Really, it's <em>package load</em> time</li>
+ <li>That's run-time, but before the "real" run-time</li>
+ <li>Moose does not rewire Perl, it's just sugar!</li>
+ <li>(but <code>MooseX::Declare</code> <em>does</em> rewire Perl)</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Enforcing Roles</h1>
+
+ <pre><code>package Comparison;
+use Moose;
+
+has [ 'left', 'right' ] => (
+ is => 'ro',
+ <span class="highlight">does => 'Comparable',</span>
+);
+</code></pre>
+
+ <ul>
+ <li>A sneak peek at type constraints</li>
+ </ul>
+</div>
+
+
+<div class="slide">
+ <h1>Roles Can Be Applied to Objects</h1>
+
+ <pre><code>use Moose::Util qw( apply_all_roles );
+
+my $fragile_person = Person->new( ... );
+apply_all_roles( $fragile_person,
+ 'IsFragile' );</code></pre>
+
+ <ul>
+ <li>Does not change the <code>Person</code> class</li>
+ <li>Works with non-Moose classes, great for monkey-patching!</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Roles Are Dirty Too</h1>
+
+ <ul>
+ <li>Once again, clean up those Moose droppings</li>
+ </ul>
+
+ <pre><code>package Comparable;
+use Moose::Role;
+
+requires 'compare';
+
+<span class="highlight">no Moose::Role;</span></code></pre>
+
+ <ul>
+ <li>But roles cannot be made immutable</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>The Zen of Roles</h1>
+
+ <ul>
+ <li>Roles represent discrete units of ...
+ <ul>
+ <li>state</li>
+ <li>behavior</li>
+ <li>interface</li>
+ </ul>
+ </li>
+ <li>Roles are shareable between unrelated classes</li>
+ <li>Roles are what a class <em>does</em>, not what it <em>is</em></li>
+ <li>Roles <em>add</em> functionality, inheritance <em>specializes</em></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Abstract Examples</h1>
+
+ <ul>
+ <li>Human <em>@ISA</em> Animal</li>
+ <li>Human <em>does</em> Toolmaker (as <em>does</em> Chimpanzee)</li>
+ <li>Car <em>@ISA</em> Vehicle</li>
+ <li>Car <em>does</em> HasEngine</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Real Examples</h1>
+
+ <ul>
+ <li>Objects representing SQL database components and queries
+ <ul>
+ <li>Schema, Table, Column, ColumnAlias</li>
+ <li>Select, Insert, Update, Delete</li>
+ </ul>
+ </li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Real Examples</h1>
+
+ <ul>
+ <li>All queries <em>do</em> HasWhereClause</li>
+ <li>Select <em>does</em> Comparable and Selectable (for subselects)</li>
+ <li>A where clause requires its components to <em>do</em> Comparable</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Roles Summary</h1>
+
+ <ul>
+ <li>Roles can define an interface with <code>requires</code></li>
+ <li>Roles can have state (attributes) and behavior (methods)</li>
+ <li>Roles can mix interface, state, & behavior</li>
+ <li>Roles are composed (flattened) into classes</li>
+ <li>Roles can do other roles</li>
+ <li>Roles can be used as a type in APIs (must do Comparable)</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Questions?</h1>
+</div>
+
+<div class="slide">
+ <h1>Exercises</h1>
+
+ <pre># cd exercises
+# perl bin/prove -lv t/02-roles.t
+
+Iterate til this passes all its tests</pre>
+</div>
+
+<div class="slide fake-slide0">
+ <h1>Part 3: Basic Attributes</h1>
+</div>
+
+<div class="slide">
+ <h1>Attributes Are Huge</h1>
+
+ <ul>
+ <li>Moose's biggest feature</li>
+ <li>The target of <em>many</em> MooseX modules</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Quick Review</h1>
+
+ <ul>
+ <li>Declared with <code>has</code></li>
+ <li>Read-only or read-write</li>
+ </ul>
+
+ <pre><code>package Shirt;
+use Moose;
+
+has 'color' => ( is => 'ro' );
+has 'is_ripped' => ( is => 'rw' );</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Read-only vs Read-write</h1>
+
+ <ul>
+ <li>Read-only is preferred</li>
+ <li>Minimize state in your application</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Required-ness</h1>
+
+ <ul>
+ <li>Required means "must be passed to the constructor"</li>
+ <li>But can be <code>undef</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Required-ness</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has first_name => (
+ is => 'ro',
+ <span class="current incremental">required => 1,</span>
+);
+
+<span class="incremental">Person->new( first_name => undef ); # ok
+Person->new(); # kaboom</span></code></pre>
+</div>
+
+<div class="slide">
+ <h1>Default and Builder</h1>
+
+ <ul>
+ <li>Attributes can have defaults</li>
+ <li>Simple non-reference scalars (number, string)</li>
+ <li>Subroutine reference</li>
+ <li>A builder method</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Default</h1>
+
+ <ul>
+ <li>Can be a non-reference scalar (including <code>undef</code>)</li>
+ </ul>
+
+ <pre><code>package Person;
+use Moose;
+
+has bank => (
+ is => 'rw',
+ default => 'Spire FCU',
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Default</h1>
+
+ <ul>
+ <li>Can be a subroutine reference</li>
+ </ul>
+
+ <pre><code>package Person;
+use Moose;
+
+has bank => (
+ is => 'rw',
+ default =>
+ sub { Bank->new(
+ name => 'Spire FCU' ) },
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Subroutine Reference Default</h1>
+
+ <ul>
+ <li>Called as a method on the object</li>
+ <li>Called anew for each object</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Why No Other Reference Types?</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has bank => (
+ is => 'rw',
+ # THIS WILL NOT WORK
+ <span class="wrong">default => Bank->new(
+ name => 'Spire FCU' ),</span>
+);</code></pre>
+
+ <ul>
+ <li>Now <strong>every</strong> person shares the <strong>same</strong> Bank object!</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Defaulting to an Empty Reference</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has packages => (
+ is => 'rw',
+ default => <span class="highlight">sub { [] }</span>,
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Builder</h1>
+
+ <ul>
+ <li>A method <em>name</em></li>
+ <li>When called, this method returns the default value</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Builder</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has bank => (
+ is => 'rw',
+ builder => '_build_bank',
+);
+
+sub _build_bank {
+ my $self = shift;
+ return Bank->new(
+ name => 'Spire FCU' );
+}</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Default vs Builder</h1>
+
+ <ul>
+ <li>Use default for simple scalars</li>
+ <li>Use default to return empty references</li>
+ <li>Use default for <em>very</em> trivial subroutine references</li>
+ <li>Use builder for everything else</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Builder Bonuses</h1>
+
+ <ul>
+ <li>Can be overridden and method modified, because it's called by <em>name</em></li>
+ <li>Roles can require a builder</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Role Requires Builder</h1>
+
+ <pre><code>package HasBank;
+use Moose::Role;
+
+requires '_build_bank';
+
+has bank => (
+ is => 'ro',
+ builder => '_build_bank',
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Lazy, Good for Nothin' Attributes</h1>
+
+ <ul>
+ <li>Normally, defaults are generated during object construction</li>
+ <li>This can be expensive</li>
+ <li>We want to default to <code>$self->size * 2</code>, but attribute initialization order is unpredictable</li>
+ <li>Use lazy attributes!</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>The Power of Dynamic Defaults</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has shoe_size => (
+ is => 'ro',
+ required => 1,
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>The Power of Dynamic Defaults</h1>
+
+ <pre><code>has shoes => (
+ is => 'ro',
+ <span class="highlight">lazy => 1,</span>
+ builder => '_build_shoes',
+);
+
+sub _build_shoes {
+ my $self = shift;
+
+ return Shoes->new(
+ size => <span class="highlight">$self->shoe_size</span> );
+}</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Lazy is Good</h1>
+
+ <ul>
+ <li>Lazy defaults are executed when the attribute is read</li>
+ <li>Can see other object attributes</li>
+ <li>Still need to watch out for circular laziness</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Clearer and Predicate</h1>
+
+ <ul>
+ <li>Attributes can have a value, including <code>undef</code>, or not</li>
+ <li>Can clear the value with a clearer method</li>
+ <li>Can check for the existence of a value with a predicate method</li>
+ <li>By default, these methods are not created</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Clearer and Predicate</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has account => (
+ is => 'ro',
+ lazy => 1,
+ builder => '_build_account',
+ <span class="highlight">clearer => '_clear_account',
+ predicate => 'has_account',</span>
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Clearer and Lazy Defaults</h1>
+
+ <ul>
+ <li>Lazy defaults are good for computed attributes</li>
+ <li>Clear the attribute when the source data changes</li>
+ <li>Recalculated at next access</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Renaming constructor arguments</h1>
+
+ <ul>
+ <li>By default, constructor names = attribute names</li>
+ <li>Use <code>init_arg</code> to change this</li>
+ <li>Set <code>init_arg => undef</code> to make it unconstructable</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Some <code>init_arg</code> examples</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has shoe_size => (
+ is => 'ro',
+ <span class="highlight">init_arg => 'foot_size',</span>
+);
+
+Person->new( <span class="wrong">shoe_size => 13</span> );
+
+my $person =
+ Person->new( <span class="right">foot_size => 13</span> );
+print $person->shoe_size;</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Some <code>init_arg</code> examples</h1>
+
+<pre><code>package Person;
+use Moose;
+
+has shoes => (
+ is => 'ro',
+ <span class="highlight">init_arg => undef,</span>
+);
+
+Person->new( <span class="wrong">shoes => Shoes->new</span> );</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Why Set <code>init_arg => undef</code>?</h1>
+
+ <ul>
+ <li>Use this with a lazy default for attributes-as-cache</li>
+ <li>Compute the value as needed</li>
+ <li>Ensure that it is always generated correctly (not set by constructor)</li>
+ <li>Use triggers or method modifiers (coming soon) to clear the value</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Attribute Inheritance</h1>
+
+ <ul>
+ <li>By default, subclasses inherit attribute as-is</li>
+ <li>Can change attribute parameters in subclasses</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Attribute Inheritance Example</h1>
+
+ <pre><code>package Employee;
+use Moose;
+
+extends 'Person';
+
+has '<span class="highlight">+first_name</span>' => (
+ default => 'Joe',
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Attribute Inheritance Warning</h1>
+
+ <ul>
+ <li>An attribute is a contract about a class's API</li>
+ <li>Don't break that contract in a subclass</li>
+ <li>Especially important in the context of types</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Changing Accessor Names</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has first_name => (
+ <span class="highlight">accessor</span> => 'first_name',
+);</code></pre>
+
+ <ul>
+ <li>The long-hand version of <code>is => 'rw'</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Changing Accessor Names</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has first_name => (
+ <span class="highlight">reader</span> => 'first_name',
+ <span class="highlight">writer</span> => undef,
+);</code></pre>
+
+ <ul>
+ <li>The long-hand version of <code>is => 'ro'</code></li>
+ </ul>
+</div>
+
+
+<div class="slide">
+ <h1>Changing Accessor Names</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has first_name => (
+ <span class="highlight">reader</span> => 'get_first_name',
+ <span class="highlight">writer</span> => 'set_first_name',
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Changing Accessor Names</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has first_name => (
+ <span class="highlight">is</span> => 'rw',
+ <span class="highlight">writer</span> => '_first_name',
+);</code></pre>
+
+ <ul>
+ <li>Can also mix-and-match <code>is</code> and explicit names</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>ETOOMUCHTYPING</h1>
+
+ <ul>
+ <li><code>MooseX::FollowPBP</code><br /><code>get_foo</code> and <code>set_foo</code></li>
+ <li><code>MooseX::SemiAffordanceAccessor</code><br /><code>foo</code> and <code>set_foo</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>ETOOMUCHTYPING</h1>
+
+ <pre><code>package Person;
+use Moose;
+<span class="highlight">use MooseX::SemiAffordanceAccessor;</span>
+
+has first_name => (
+ is => 'rw',
+);</code></pre>
+
+ <ul>
+ <li>Creates <code>first_name</code> and <code>set_first_name</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Basic Attributes Summary</h1>
+
+ <ul>
+ <li>Attributes can be <code>required</code></li>
+ <li>Attributes can have a <code>default</code> or <code>builder</code></li>
+ <li>Attributes with a default or builder can be <code>lazy</code></li>
+ <li>Attributes can have a <code>clearer</code> and/or <code>predicate</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Basic Attributes Summary</h1>
+
+ <ul>
+ <li>An attribute's constructor name can be changed with <code>init_arg</code></li>
+ <li>A subclass can alter its parents' attributes</li>
+ <li>Attribute accessor names can be changed</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Questions?</h1>
+</div>
+
+<div class="slide">
+ <h1>Exercises</h1>
+
+ <pre># cd exercises
+# perl bin/prove -lv \
+ t/03-basic-attributes.t
+
+Iterate til this passes all its tests</pre>
+</div>
+
+<div class="slide fake-slide0">
+ <h1>Part 4: Method Modifiers</h1>
+</div>
+
+<div class="slide">
+ <h1>What is a Method Modifier</h1>
+
+ <ul>
+ <li>Apply to an existing method</li>
+ <li>... that comes from a parent class, the current class, or a role</li>
+ <li>Roles can provide modifiers that are applied at composition time</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>What Are Method Modifiers For?</h1>
+
+ <ul>
+ <li>"Inject" behavior</li>
+ <li>Add behavior to generated methods (accessors, delegations)</li>
+ <li>Added from a role, can modify existing behavior</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Before and After</h1>
+
+ <ul>
+ <li>Simplest modifiers - <code>before</code> and <code>after</code></li>
+ <li>Guess when they run!</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Uses for <code>before</code></h1>
+
+ <ul>
+ <li>As a pre-call check</li>
+ </ul>
+
+ <pre><code>package Person;
+use Moose;
+
+before work => sub {
+ my $self = shift;
+ die 'I have no job!'
+ unless $self->has_title;
+};</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Uses for <code>before</code></h1>
+
+ <ul>
+ <li>Logging/Debugging</li>
+ </ul>
+
+ <pre><code>package Person;
+use Moose;
+
+before work => sub {
+ my $self = shift;
+ return unless $DEBUG;
+
+ warn "Called work on ",
+ $self->full_name,
+ "with the arguments: [@_]\n";
+};</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Uses for <code>after</code></h1>
+
+ <ul>
+ <li>Also works for logging/debugging</li>
+ <li>Post-X side-effects (recording audit info)</li>
+ </ul>
+
+ <pre><code>package Person;
+use Moose;
+
+after work => sub {
+ my $self = shift;
+ $self->work_count(
+ $self->work_count + 1 );
+};</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Other Uses</h1>
+
+ <ul>
+ <li>Modifiers are useful for adding behavior to generated methods</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>More Modifier Examples</h1>
+
+ <pre><code>has password => (
+ is => 'rw',
+ clearer => 'clear_password',
+);
+has hashed_password => (
+ is => 'ro',
+ builder => '_build_hashed_password',
+ clearer => '_clear_hashed_password',
+);
+after clear_password => sub {
+ my $self = shift;
+ $self->_clear_hashed_password;
+};</code></pre>
+</div>
+
+<div class="slide">
+ <h1><code>before</code> and <code>after</code> Limitations</h1>
+
+ <ul>
+ <li>Cannot alter method parameters</li>
+ <li>Cannot alter return value</li>
+ <li>But <strong>can</strong> throw an exception</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>The <code>around</code> Modifier</h1>
+
+ <ul>
+ <li>The big gun</li>
+ <li>Can alter parameters <strong>and/or</strong> return values</li>
+ <li>Can skip calling the wrapped method entirely</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>The power of <code>around</code></h1>
+
+ <pre><code>around insert => sub {
+ my $orig = shift;
+ my $self = shift;
+
+ $self->_validate_insert(@_);
+
+ my $new_user =
+ $self->$orig(
+ $self->_munge_insert(@_) );
+
+ $new_user->_assign_uri;
+ return $new_user;
+};</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Modifier Order</h1>
+
+ <ul>
+ <li>Before runs in order from last to first</li>
+ <li>After runs in order from first to last</li>
+ <li>Around runs in order from last to first</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Modifier Order Illustrated</h1>
+
+<pre>
+<span class="current incremental">before 2
+ before 1</span>
+ <span class="incremental">around 2
+ around 1</span>
+ <span class="incremental">wrapped method</span>
+ <span class="incremental">around 1
+ around 2</span>
+ <span class="incremental">after 1
+after 2</span>
+</pre>
+</div>
+
+<div class="slide">
+ <h1>Modifiers in Roles</h1>
+
+ <ul>
+ <li>Roles can use these modifiers</li>
+ <li>Very powerful!</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Modifiers in Roles</h1>
+
+ <pre><code>package IsUnreliable;
+use Moose::Role;
+
+<span class="highlight">requires 'run';
+
+around run</span> => sub {
+ my $orig = shift;
+ my $self = shift;
+
+ return if rand(1) < 0.5;
+
+ return $self->$orig(@_);
+};</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Method Modifiers Summary</h1>
+
+ <ul>
+ <li>Use <code>before</code> and <code>after</code> for ...
+ <ul>
+ <li>logging</li>
+ <li>pre- or post-validation</li>
+ <li>to add behavior to generated methods</li>
+ </ul>
+ </li>
+ <li>These two modifiers cannot change parameters or return values</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Method Modifiers Summary</h1>
+
+ <ul>
+ <li>Use <code>around</code> to ...
+ <ul>
+ <li>alter parameters passed to the original method</li>
+ <li>alter the return value of the original method</li>
+ <li>not call the original method at all (or call a <em>different</em> method)</li>
+ </ul>
+ </li>
+ <li>When using modifiers in a role, require the modified method</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Questions?</h1>
+</div>
+
+<div class="slide">
+ <h1>Exercises</h1>
+
+ <pre># cd exercises
+# perl bin/prove -lv \
+ t/04-method-modifiers.t
+
+Iterate til this passes all its tests</pre>
+</div>
+
+<div class="slide fake-slide0">
+ <h1>Part 5: Types</h1>
+</div>
+
+<div class="slide">
+ <h1>A Type System for Perl</h1>
+
+ <ul>
+ <li>Sort of ...</li>
+ <li><em>Variables</em> are not typed</li>
+ <li>Attributes can have types</li>
+ <li>MooseX modules let you define method signatures</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Components of a Moose Type</h1>
+
+ <ul>
+ <li>A type is a name and a constraint</li>
+ <li>Types have a hierarchy</li>
+ <li>Constraints are cumulative from parents</li>
+ <li>Types can have associated coercions</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Built-in Type Hierarchy</h1>
+
+ <pre>
+Any
+Item
+ Bool
+ Maybe[`a]
+ Undef
+ Defined
+ Value
+ Str
+ Num
+ Int
+ ClassName
+ RoleName
+</pre>
+</div>
+
+<div class="slide">
+ <h1>Built-in Type Hierarchy</h1>
+
+<pre>
+(Item)
+ (Defined)
+ (Value)
+ Ref
+ ScalarRef
+ ArrayRef[`a]
+ HashRef[`a]
+ CodeRef
+ RegexpRef
+ GlobRef
+ FileHandle
+ Object
+</pre>
+</div>
+
+<div class="slide">
+ <h1>Bool</h1>
+
+ <h2>True</h2>
+ <pre><code>1</code></pre>
+
+ <h2>False</h2>
+ <pre><code>0
+'0'
+''
+undef</code></pre>
+
+ <ul>
+ <li>Like Perl's <code>if ($foo)</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Value (and subtypes)</h1>
+
+ <ul>
+ <li><code>Value</code> is true when <code>! ref $thing</code></li>
+ <li><code>Value</code> and <code>Str</code> are effectively the same, but <code>Str</code> is more expressive</li>
+ <li><code>Num</code> is true when a <code>$scalar</code> looks like a number</li>
+ <li>An overloaded object which numifies does not pass the <code>Num</code> constraint!</li>
+ <li>Perl 5's overloading is hopelessly broken</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>ClassName and RoleName</h1>
+
+ <ul>
+ <li>A string with a package name</li>
+ <li>The package <strong>must already be loaded</strong></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Parameterizable Types</h1>
+
+ <ul>
+ <li>What does <code>ArrayRef[`a]</code> mean?</li>
+ <li><code>s/`a/Int/</code> (or <code>Str</code> or ...)</li>
+ <li>When you use it you can write ...
+ <ul>
+ <li><code>ArrayRef</code> (== <code>ArrayRef[Item]</code>)</li>
+ <li><code>ArrayRef[Str]</code></li>
+ <li><code>ArrayRef[MyTypeName]</code></li>
+ <li><code>ArrayRef[HashRef[Maybe[Int]]]</code></li>
+ </ul>
+ </li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Maybe[`a]</h1>
+
+ <ul>
+ <li>Maybe means either the named type or <code>undef</code></li>
+ <li><code>Maybe[Int]</code> accepts integers or <code>undef</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Type Union</h1>
+
+ <ul>
+ <li>This or that (or that or ...)</li>
+ <li><code>Int | ArrayRef[Int]</code></li>
+ <li>But use a coercion instead when possible</li>
+ <li>Or use a <code>role_type</code>, <code>duck_type</code>, or anything not a union</li>
+ <li>A union is often a code smell</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Making Your Own Types</h1>
+
+ <pre><code>use Moose::Util::TypeConstraints;
+
+<span class="incremental current">subtype 'PositiveInt',</span>
+ <span class="incremental">as 'Int',</span>
+ <span class="incremental">where { $_ > 0 },</span>
+ <span class="incremental">message
+ { "The value you provided ($_)"
+ . " was not a positive int." };</span>
+
+has size => (
+ is => 'ro',
+ <span class="incremental">isa => 'PositiveInt',</span>
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Automatic Types</h1>
+
+ <ul>
+ <li>Moose creates a type for every Moose class and role</li>
+ <li>Unknown names are assumed to be classes</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Automatic Types</h1>
+
+ <pre><code>package Employee;
+use Moose;
+
+has manager => (
+ is => 'rw',
+ <span class="highlight">isa => 'Employee',</span>
+);
+
+has start_date => (
+ is => 'ro',
+ <span class="highlight">isa => 'DateTime',</span>
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Subtype Shortcuts - <code>class_type</code></h1>
+
+ <pre><code>use Moose::Util::TypeConstraints;
+class_type 'DateTime';</code></pre>
+
+<hr />
+
+<pre><code>subtype 'DateTime',
+ as 'Object',
+ where { $_->isa('DateTime') },
+ message { ... };</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Subtype Shortcuts - <code>role_type</code></h1>
+
+ <pre><code>use Moose::Util::TypeConstraints;
+role_type 'Printable';</code></pre>
+
+<hr />
+
+<pre><code>subtype 'Printable',
+ as 'Object',
+ where
+ { Moose::Util::does_role(
+ $_, 'Printable' ) },
+ message { ... };</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Subtype Shortcuts - <code>duck_type</code></h1>
+
+ <pre><code>use Moose::Util::TypeConstraints;
+duck_type Car => qw( run break_down );</code></pre>
+
+<hr />
+
+<pre><code>subtype 'Car',
+ as 'Object',
+ where { all { $_->can($_) }
+ qw( run break_down ) },
+ message { ... };</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Subtype Shortcuts - <code>enum</code></h1>
+
+ <pre><code>use Moose::Util::TypeConstraints;
+enum Color => qw( red blue green );</code></pre>
+
+<hr />
+
+<pre><code>my %ok = map { $_ => 1 }
+ qw( red blue green );
+
+subtype 'Color'
+ as 'Str',
+ where { $ok{$_} },
+ message { ... };</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Anonymous Subtypes</h1>
+
+ <pre><code>package Person;
+
+<span class="highlight">my $posint =
+ subtype as 'Int', where { $_ > 0 };</span>
+
+has size => (
+ is => 'ro',
+ <span class="highlight">isa => $posint,</span>
+);</code></pre>
+
+ <ul>
+ <li>Shortcuts have anonymous forms as well</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Coercions</h1>
+
+ <pre><code>use Moose::Util::TypeConstraints;
+
+subtype 'UCStr',
+ as 'Str',
+ where { ! /[a-z]/ };</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Coercions</h1>
+
+ <pre><code><span class="incremental current">coerce 'UCStr',</span>
+ <span class="incremental">from 'Str',</span>
+ <span class="incremental">via { uc };</span>
+
+has shouty_name => (
+ is => 'ro',
+ isa => 'UCStr',
+ <span class="incremental">coerce => 1,</span>
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Coercion Examples</h1>
+
+ <pre><code>subtype 'My::DateTime',
+ as class_type 'DateTime';
+
+coerce 'My::DateTime',
+ from 'HashRef',
+ via { DateTime->new( %{$_} ) };
+
+coerce 'My::DateTime',
+ from 'Int',
+ via { DateTime->from_epoch(
+ epoch => $_ ) };</code></pre>
+
+ <ul>
+ <li>Use coercion to inflate a value</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Coercion Examples</h1>
+
+ <pre><code># BAD CODE - DO NOT COPY
+coerce 'ArrayRef[Int]',
+ from 'Int',
+ via { [ $_ ] };</code></pre>
+
+ <ul>
+ <li>Instead of union - <code style="white-space: nowrap">Int | ArrayRef[Int]</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Using Types with Attributes</h1>
+
+ <pre><code>package Person;
+
+has height => (
+ is => 'rw',
+ <span class="highlight">isa => 'Num',</span>
+);
+
+has favorite_numbers => (
+ is => 'rw',
+ <span class="highlight">isa => 'ArrayRef[Int]',
+ coerce => 1,</span>
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>More Droppings</h1>
+
+ <ul>
+ <li><code>Moose::Util::TypeConstraints</code> also needs cleanup</li>
+ </ul>
+
+ <pre><code>package Person;
+
+use Moose;
+use Moose::Util::TypeConstraints;
+
+subtype ...;
+
+no Moose;
+<span class="highlight">no Moose::Util::TypeConstraints;</span></code></pre>
+</div>
+
+<div class="slide">
+ <h1>Questions So Far?</h1>
+</div>
+
+<div class="slide">
+ <h1>Exercises</h1>
+
+ <pre># cd exercises
+# perl bin/prove -lv t/05-types.t
+
+Iterate til this passes all its tests</pre>
+</div>
+
+<div class="slide">
+ <h1>Typed Methods (Low-tech)</h1>
+
+ <pre class="medium"><code>package Person;
+<span class="highlight">use MooseX::Params::Validate qw( validated_list );</span>
+
+sub work {
+ my $self = shift;
+ <span class="highlight">my ( $tasks, $can_rest ) =
+ validated_list(
+ \@_,
+ tasks =>
+ { isa => 'ArrayRef[Task]',
+ coerce => 1 },
+ can_rest =>
+ { isa => 'Bool',
+ default => 0 },
+ );</span>
+ ...
+}</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Typed Methods (High-tech)</h1>
+
+ <pre class="medium"><code>package Person;
+
+<span class="highlight">use MooseX::Method::Signatures;</span>
+
+<span class="highlight">method work ( ArrayRef[Task] :$tasks,
+ Bool :$can_rest = 0 )</span> {
+ my $self = shift;
+
+ ...
+}</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Digression: The Type Registry</h1>
+
+ <ul>
+ <li>Types are actually <code>Moose::Meta::TypeConstraint</code> <em>objects</em></li>
+ <li>Stored in an interpreter-global registry mapping names to objects</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Danger!</h1>
+
+ <ul>
+ <li>Coercions are attached to type objects</li>
+ <li>Therefore also global</li>
+ <li>Name conflicts between modules!</li>
+ <li>Coercion conflicts between modules!</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Namespace Fix</h1>
+
+ <ul>
+ <li>Use some sort of pseudo-namespacing scheme</li>
+ <li>Never coerce directly to a class name, or <em>to</em> built-in types</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Namespace Fix</h1>
+
+ <pre><code>use Moose::Util::TypeConstraints;
+subtype <span class="highlight">'MyApp::Type::DateTime',</span>
+ as 'DateTime';
+
+<span class="highlight">coerce 'MyApp::Type::DateTime',</span>
+ from 'HashRef',
+ via { DateTime->new( %{$_} ) }
+
+has creation_date => (
+ is => 'ro',
+ <span class="highlight">isa => 'MyApp::Type::DateTime',</span>
+ coerce => 1,
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Namespace Fix</h1>
+
+ <pre><code>subtype 'MyApp::Type::ArrayOfInt',
+ as 'ArrayRef[Int]';
+
+coerce 'MyApp::Type::ArrayOfInt',
+ from 'Int',
+ via { [ $_ ] };</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Namespace Fix Pros and Cons</h1>
+
+ <ul>
+ <li><span class="right">Relatively simple</span></li>
+ <li><span class="right">Already built into Moose</span></li>
+ <li><span class="wrong">Conflates type and module namespaces</span></li>
+ <li><span class="wrong">Type names are strings, so typos are easy to make and may be hard to find</span></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Types</h1>
+
+ <pre><code>package MyApp::Types;
+
+use MooseX::Types
+ <span class="highlight">-declare => [ qw( ArrayOfInt ) ]</span>;
+use MooseX::Types::Moose
+ qw( ArrayRef Int );
+
+subtype <span class="highlight">ArrayOfInt</span>,
+ as ArrayRef[Int];
+
+coerce <span class="highlight">ArrayOfInt</span>
+ from Int,
+ via { [ $_ ] };</code></pre>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Types</h1>
+
+ <pre><code>package MyApp::Account;
+
+use MyApp::Types qw( ArrayOfInt );
+
+has transaction_history => (
+ is => 'rw',
+ isa => ArrayOfInt,
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Types</h1>
+
+ <ul>
+ <li>Type names are exported functions, catches typos early</li>
+ <li>Types must be pre-declared</li>
+ <li>Types are stored with namespaces internally, but you use short names</li>
+ <li>Import existing Moose types as functions from <code>MooseX::Types::Moose</code></li>
+ <li>Still need string names for things like <code>ArrayRef['Email::Address']</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Types Pros and Cons</h1>
+
+ <ul>
+ <li><span class="right">Catches typos at compile time</span></li>
+ <li><span class="right">Automatic namespacing</span></li>
+ <li><span class="wrong">One more thing to install and learn</span></li>
+ <li><span class="wrong">Every name is typed twice (declared and then defined)</span></li>
+ <li><span class="wrong">Still stuck with strings when referring to class or role names</span></li>
+ <li><span class="wrong">Coercion gotcha from earlier still applies to types exported from <code>MooseX::Types::Moose</code></span></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Recommendation</h1>
+
+ <ul>
+ <li>Use <code>MooseX::Types</code></li>
+ <li>Compile time error catching and automatic namespacing are huge wins</li>
+ <li>Docs from <code>Moose::Util::TypeConstraints</code> are 98% compatible with <code>MooseX::Types</code> anyway</li>
+ <li>A function exported by a type library works wherever a type name would</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Questions?</h1>
+</div>
+
+<div class="slide fake-slide0">
+ <h1>Part 6: Advanced Attributes</h1>
+</div>
+
+<div class="slide">
+ <h1>Weak References</h1>
+
+ <ul>
+ <li>A weak reference lets you avoid circular references</li>
+ <li>Weak references do not increase the reference count</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Circular Reference Illustrated</h1>
+
+ <pre><code>my $foo = {};
+my $bar = { foo => $foo };
+$foo->{bar} = $bar;</code></pre>
+
+ <ul>
+ <li>Neither <code>$foo</code> nor <code>$bar</code> go out of scope<br />
+ (until the program exits)</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Weakening Circular References</h1>
+
+ <pre><code>use Scalar::Util qw( weaken );
+
+my $foo = {};
+my $bar = { foo => $foo };
+$foo->{bar} = $bar;
+weaken $foo->{bar}</code></pre>
+
+ <ul>
+ <li>When <code>$bar</code> goes out of scope, <code>$foo->{bar}</code> becomes <code>undef</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Circular References in Attributes</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has name => ( is => 'ro' );
+has friend => ( is => 'rw' );
+
+my $alice = Person->new( name => 'Alice' );
+my $bob = Person->new( name => 'Bob' );
+$bob->friend($alice);
+$alice->friend($bob);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>The Fix</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has name => ( is => 'ro' );
+has friend => ( is => 'rw',
+ <span class="highlight">weak_ref => 1</span> );
+
+my $alice = Person->new( name => 'Alice' );
+my $bob = Person->new( name => 'Bob' );
+$bob->friend($alice);
+$alice->friend($bob);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Under the Hood</h1>
+
+ <ul>
+ <li>A <code>weak_ref</code> attribute calls <code>weaken</code> ...
+ <ul>
+ <li>during object construction</li>
+ <li>when the attribute is set via a writer</li>
+ </ul>
+ </li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Triggers</h1>
+
+ <ul>
+ <li>A code reference run after an attribute is <em>set</em></li>
+ <li>Like an <code>after</code> modifier, but makes intentions clearer</li>
+ </ul>
+
+ <h2 class="wrong">Gross</h2>
+
+ <pre><code>after salary_level => {
+ my $self = shift;
+ <span class="highlight">return unless @_;</span>
+ $self->clear_salary;
+};</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Use a Trigger Instead</h1>
+
+ <h2 class="right">Cleaner</h2>
+
+ <pre><code>has salary_level => (
+ is => 'rw',
+ trigger =>
+ sub { $_[0]->clear_salary },
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Trigger Arguments</h1>
+
+ <ul>
+ <li><code>$self</code></li>
+ <li><code>$new_value</code></li>
+ <li><code>$old_value</code> - if one exists</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Delegation</h1>
+
+ <ul>
+ <li>Attributes can be objects</li>
+ <li>Delegation transparently calls methods on those objects</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Delegation Examples</h1>
+
+ <pre><code>package Person;
+
+has lungs => (
+ is => 'ro',
+ isa => 'Lungs',
+ <span class="highlight">handles => [ 'inhale', 'exhale' ],</span>
+);</code></pre>
+
+ <ul>
+ <li>Creates <code>$person->inhale</code> and <code>->exhale</code> methods</li>
+ <li>Internally calls <code>$person->lungs->inhale</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Why Delegation?</h1>
+
+ <ul>
+ <li>Reduce the number of classes exposed</li>
+ <li>Re-arrange class internals -<br />
+ turn a method into an attribute with delegation</li>
+ <li>Provide convenenience methods</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Moose's <code>handles</code> Parameter</h1>
+
+ <ul>
+ <li>Accepts many arguments ...
+ <ul>
+ <li>Array reference - list of methods to delegate as-is</li>
+ <li>Hash reference - map of method names</li>
+ <li>Regex - delegates all matching methods</li>
+ <li>Role name - delegates all methods in the role</li>
+ <li>Sub reference - does something complicated ;)</li>
+ </ul>
+ </li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Array Reference</h1>
+
+ <ul>
+ <li>1-to-1 mapping</li>
+ <li>Takes each method name and creates a simple delegation from the delegating class to the delegatee attribute</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Hash Reference</h1>
+
+ <ul>
+ <li>Mapping of names in the delegating class to the delegatee class</li>
+ </ul>
+
+ <pre><code>package Person;
+use Moose;
+has account => (
+ is => 'ro',
+ isa => 'BankAccount',
+ <span class="highlight">handles => {
+ receive_money => 'deposit',
+ give_money => 'withdraw',
+ },</span>
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Hash Reference Detailed</h1>
+
+ <pre><code> handles => {
+ receive_money => 'deposit',
+ give_money => 'withdraw',
+ },</code></pre>
+
+ <ul>
+ <li><code>$person->receive_money</code> = <code>$person->account->deposit</code></li>
+ <li><code>$person->give_money</code> = <code>$person->account->withdraw</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Regex</h1>
+
+ <pre><code>package Person;
+use Moose;
+
+has name => (
+ is => 'ro',
+ isa => 'Name',
+ handles => qr/.*/,
+);</code></pre>
+
+ <ul>
+ <li>Creates a delegation for every method in the Name class</li>
+ <li>Excludes <code>meta</code> and methods inherited from <code>Moose::Object</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Role Name</h1>
+
+ <pre><code>package Auditor;
+use Moose::Role;
+sub record_change { ... }
+sub change_history { ... }
+
+package Account;
+use Moose;
+
+has history => (
+ is => 'ro',
+ does => 'Auditor',
+ <span class="highlight">handles => 'Auditor',</span>
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Role Name Detailed</h1>
+
+ <ul>
+ <li>Account gets delegate methods for each method in the <code>Auditor</code> role
+ <ul>
+ <li>record_history</li>
+ <li>change_history</li>
+ </ul>
+ </li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Native Delegation</h1>
+
+ <ul>
+ <li>Delegate to <em>unblessed</em> Perl types</li>
+ <li>Scalar, array or hash ref, etc</li>
+ <li>Treat Perl types as objects</li>
+ <li>Still uses <code>handles</code></li>
+ <li>Pretend that native Perl types have methods</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Native Delegation - Array(Ref)</h1>
+
+ <ul>
+ <li>Methods include:
+ <ul>
+ <li><code>push</code></li>
+ <li><code>shift</code></li>
+ <li><code>elements</code> - returns all elements</li>
+ <li><code>count</code></li>
+ <li><code>is_empty</code></li>
+ <li>quite a few more</li>
+ </ul>
+ </li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Native Delegation - Array(Ref)</h1>
+
+ <pre><code>package Person;
+use Moose;
+has _favorite_numbers => (
+ traits => [ 'Array' ],
+ isa => 'ArrayRef[Int]',
+ default => sub { [] },
+ init_arg => undef,
+ <span class="highlight">handles =>
+ { favorite_numbers => 'elements',
+ add_favorite_number => 'push',
+ },</span>
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Native Delegation - Array(Ref)</h1>
+
+ <pre><code>my $person = Person->new();
+
+$person->add_favorite_number(7);
+$person->add_favorite_number(42);
+
+print "$_\n"
+ for $person->favorite_numbers;
+
+# 7
+# 42</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Native Delegation</h1>
+
+ <ul>
+ <li>Native types are ...
+ <ul>
+ <li>Number - <code>add</code>, <code>mul</code>, ...</li>
+ <li>String - <code>append</code>, <code>chop</code>, ...</li>
+ <li>Counter - <code>inc</code>, <code>dec</code>, ...</li>
+ <li>Bool - <code>set</code>, <code>toggle</code>, ...</li>
+ <li>Hash - <code>get</code>, <code>set</code>, ...</li>
+ <li>Array - already saw it</li>
+ <li>Code - <code>execute</code> and <code>execute_method</code></li>
+ </ul>
+ </li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Curried Delegation</h1>
+
+ <ul>
+ <li>A delegation with some preset arguments</li>
+ <li>Works with object or Native delegation</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Curried Delegation</h1>
+
+ <pre><code>package Person;
+use Moose;
+has account => (
+ is => 'ro',
+ isa => 'BankAccount',
+ handles => {
+ receive_100 =>
+ <span class="highlight">[ 'deposit', 100 ]</span>,
+ give_100 =>
+ <span class="highlight">[ 'withdraw', 100 ]</span>
+ },
+);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Curried Delegation</h1>
+
+ <pre><code>$person->receive_100;
+# really is
+$person->account->deposit(100);</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Traits and Metaclasses</h1>
+
+ <ul>
+ <li>The ultimate in customization</li>
+ <li>Per attribute metaclasses</li>
+ <li>Per attribute roles applied to the attribute metaclass</li>
+ <li>Change the meta-level behavior</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Traits and Metaclasses</h1>
+
+ <ul>
+ <li>The default metaclass is <code>Moose::Meta::Attribute</code></li>
+ <li>Controls accessor generation, defaults, delegation, etc.</li>
+ <li>Adding a role to this metaclass (or replacing it) allows for infinite customization</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Traits and Metaclasses</h1>
+
+ <ul>
+ <li>Can add/alter/remove an attribute parameter (from <code>has</code>)</li>
+ <li>Can change behavior of created attribute</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Simple Trait Example</h1>
+
+ <pre><code>package Person;
+use Moose;
+use MooseX::LabeledAttributes;
+
+has ssn => (
+ <span class="highlight">traits => [ 'Labeled' ],</span>
+ is => 'ro',
+ isa => 'Str',
+ <span class="highlight">label => 'Social Security Number',</span>
+);
+print <span class="highlight">Person->meta
+ ->get_attribute('ssn')->label;</span></code></pre>
+</div>
+
+<div class="slide">
+ <h1>Simple Metaclass Example</h1>
+
+ <pre><code>package Person;
+use Moose;
+use MooseX::LabeledAttributes;
+
+has ssn => (
+ <span class="highlight">metaclass =>
+ 'MooseX::Meta::Attribute::Labeled',</span>
+ is => 'ro',
+ isa => 'Str',
+ <span class="highlight">label => 'Social Security Number',</span>
+);
+print <span class="highlight">Person->meta
+ ->get_attribute('ssn')->label;</span></code></pre>
+</div>
+
+<div class="slide">
+ <h1>Traits vs Metaclass</h1>
+
+ <ul>
+ <li>Can apply any mix of traits to an attribute</li>
+ <li>But just one metaclass</li>
+ <li>Traits (aka roles) can cooperate</li>
+ <li>Metaclasses require you to pick just one</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Advanced Attributes Summary</h1>
+
+ <ul>
+ <li>Use <code>weak_ref</code> to avoid circular references</li>
+ <li>Use trigger to do an action post-attribute write</li>
+ <li>Use delegations to hide "internal" objects</li>
+ <li>Use native delegations to treat Perl types as objects</li>
+ <li>Traits and metaclasses let you extend Moose's core attribute features</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Questions?</h1>
+</div>
+
+<div class="slide">
+ <h1>Exercises</h1>
+
+ <pre># cd exercises
+# perl bin/prove -lv \
+ t/06-advanced-attributes.t
+
+Iterate til this passes all its tests</pre>
+</div>
+
+<div class="slide">
+ <h1>CYOA</h1>
+
+ <p>
+ If there is time, keep going ...
+ </p>
+
+ <p>
+ Otherwise, jump to slide 269 ...
+ </p>
+</div>
+
+<div class="slide fake-slide0">
+ <h1>Bonus: A Brief Tour of MooseX</h1>
+</div>
+
+<div class="slide">
+ <h1>Notable MX Modules on CPAN</h1>
+
+ <ul>
+ <li><strong>Not comprehensive</strong></li>
+ <li>188 MooseX distributions on CPAN as of 02/03/2011</li>
+ <li>Some of them are crap</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>Already Mentioned Several</h1>
+
+ <ul>
+ <li><code>MooseX::NonMoose</code> - best solution for subclassing non-Moose parents</li>
+ <li><code>MooseX::Declare</code> - <em>real</em> Perl 5 OO</li>
+ <li><code>MooseX::FollowPBP</code> and <code>MooseX::SemiAffordanceAccessor</code></li>
+ <li><code>MooseX::Params::Validate</code> and <code>MooseX::Method::Signatures</code></li>
+ <li><code>MooseX::Types</code></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Declare</h1>
+
+<pre><code>use MooseX::Declare;
+use 5.12.0; # for say
+
+class Person {
+ has greeting =>
+ ( is => 'ro', isa => 'Str' );
+
+ method speak {
+ say $self->greeting;
+ }
+}</code></pre>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Declare</h1>
+
+ <ul>
+ <li>Still experimental-ish, but seeing more and more use</li>
+ <li><strong>Not</strong> a source filter!</li>
+ <li>Hooks into the Perl parser rather than filtering all your code</li>
+ <li>But not supported by <code>PPI</code>, <code>perltidy</code>, etc. (yet?)</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>MooseX::StrictConstructor</h1>
+
+ <ul>
+ <li>By default, unknown constructor arguments are ignored</li>
+ <li>MX::StrictConstructor turns these into an error</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>MooseX::StrictConstructor</h1>
+
+ <pre><code>package Person;
+
+use Moose;
+<span class="highlight">use MooseX::StrictConstructor;</span>
+
+has name => ( is => 'ro' );
+
+Person->new
+ ( na<span class="wrong">n</span>e => 'Ringo Shiina' ); # kaboom</code></pre>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Traits</h1>
+
+ <ul>
+ <li>Combines object construction and role application</li>
+ <li>Makes it easy to create one-off customized objects</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Traits</h1>
+
+ <pre><code>package MyApp::Thingy;
+use Moose;
+
+<span class="highlight">with 'MooseX::Traits';</span>
+
+my $thing =
+ MyApp::Thingy-><span class="highlight">new_with_traits</span>
+ ( <span class="highlight">traits => [ 'Foo', 'Bar' ],</span>
+ size => 42 );</code></pre>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Getopt</h1>
+
+ <ul>
+ <li>Makes command-line interface programs easy!</li>
+ <li>Construct an object from CLI arguments</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Getopt</h1>
+
+ <pre><code>package App::CLI;
+use Moose;
+
+<span class="highlight">with 'MooseX::Getopt';</span>
+
+has file =>
+ ( is => 'ro', required => 1 );
+has filters =>
+ ( is => 'ro', isa => 'ArrayRef[Str]' );
+
+sub run { ... }</code></pre>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Getopt</h1>
+
+ <ul>
+ <li>Then call it like this:</li>
+ </ul>
+
+<pre><code>#!/usr/bin/perl
+
+use App::CLI;
+
+<span class="highlight">App::CLI->new_with_options()</span>->run();</code></pre>
+
+<pre>$ myapp-cli \
+ --file foo \
+ --filters compress \
+ --filters sanitize</pre>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Clone</h1>
+
+ <pre><code>package Person;
+
+use Moose;
+<span class="highlight">with 'MooseX::Clone';</span>
+
+my $person = Person->new;
+my $clone = <span class="highlight">$person->clone;</span></code></pre>
+</div>
+
+<div class="slide">
+ <h1>MooseX::NonMoose</h1>
+
+ <ul>
+ <li>Highly recommended for subclassing non-Moose parents</li>
+ <li>Gets all the little annoying details right</li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Role::Parameterized</h1>
+
+ <pre><code>package HasCollection;
+<span class="current incremental">use MooseX::Role::Parameterized;</span>
+<span class="incremental">parameter type => ( isa => 'Str',
+ default => 'Item' );</span>
+<span class="incremental">role {
+ my $p = shift;
+
+ my $type =
+ 'ArrayRef[' . $p->type() . ']';
+ has collection =>
+ ( is => 'ro',
+ isa => $type );
+};</span></code></pre>
+</div>
+
+<div class="slide">
+ <h1>MooseX::Role::Parameterized</h1>
+
+ <pre><code>package Person;
+
+use Moose;
+with HasCollection => { type => 'Int' };</code></pre>
+</div>
+
+<div class="slide">
+ <h1>Questions?</h1>
+</div>
+
+<div class="slide">
+ <h1>Moose-using Modules</h1>
+
+ <p>
+ For further reading, a few modules which use Moose ...
+ </p>
+
+ <ul>
+ <li><a href="http://search.cpan.org/dist/Catalyst-Runtime">Catalyst</a></li>
+ <li><a href="http://search.cpan.org/dist/CHI">CHI</a></li>
+ <li><a href="http://search.cpan.org/dist/Devel-REPL">Devel::REPL</a></li>
+ <li><a href="http://search.cpan.org/dist/Email-Sender">Email::Sender</a></li>
+ <li><a href="http://search.cpan.org/dist/Fey">Fey</a></li>
+ <li><a href="http://search.cpan.org/dist/Net-Twitter">Net::Twitter</a></li>
+ </ul>
+</div>
+
+<div class="slide">
+ <h1>More Information</h1>
+
+ <ul>
+ <li><a href="http://moose.perl.org/">http://moose.perl.org/</a></li>
+ <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>
+ <li><a href="irc://irc.perl.org/#moose">irc://irc.perl.org/#moose</a></li>
+ <li>mailing list - <a href="mailto:moose@perl.org">moose@perl.org</a></li>
+ <li>Slides and exercises are in Moose's git repo:
+ <br />
+ <span style="font-size:80%; white-space: nowrap">git://git.moose.perl.org/moose-presentations.git</span></li>
+ </ul>
+</div>
+
+<div class="slide fake-slide0">
+ <h1>The End</h1>
+</div>
+
+</div>
+</body>
+</html>
+
+<!--
+
+Copyright 2009 David Rolsky. All Rights Reserved.
+
+This work is licensed under a Creative Commons Attribution-Share Alike
+3.0 United States License See
+http://creativecommons.org/licenses/by-sa/3.0/us/ for details.
+
+-->
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