<h1>Value (and subtypes)</h1>
<ul>
- <li>Value is true when <code>! ref $thing</code></li>
+ <li><code>Value</code> is true when <code>! ref $thing</code></li>
+ <li><code>Value</code> and <code>Str</code> are effectively the same, but <code>Str</code> is more expressive</li>
<li>An overloaded object which numifies does not pass the <code>Num</code> constraint!</li>
<li>Perl 5's overloading is hopelessly broken</li>
</ul>
</div>
<div class="slide">
- <h1>Union Types</h1>
+ <h1>Type Union</h1>
<ul>
<li>This or that (or that or ...)</li>
<li><code>Int | ArrayRef[Int]</code></li>
<li>But use a coercion instead when possible</li>
+ <li>Or use a <code>role_type</code>, <code>duck_type</code>, or anything not a union</li>
+ <li>A union is often a code smell</li>
</ul>
</div>
</div>
<div class="slide">
+ <h1>Coercion Examples</h1>
+
+ <pre><code>subtype 'My::DateTime',
+ as class_type 'DateTime';
+
+coerce 'My::DateTime',
+ from 'HashRef',
+ via { DateTime->new( %{$_} ) };
+
+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>coerce 'ArrayRef[Int]',
+ from 'Int',
+ via { [ $_ ] };</code></pre>
+
+ <ul>
+ <li>Coerce instead of a union like <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;
+
+use Moose::Util::TypeConstraints;
+
+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>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, $can_rest ) =
+ validated_list(
+ \@_,
+ tasks =>
+ { isa => 'ArrayRef[Task]',
+ coerce =>1 },
+ can_rest =>
+ { isa => 'Bool',
+ default => 0 },
+ );</span>
+
+ ...
+}</code></pre>
+
+<div class="slide">
+ <h1>Typed Methods (High-tech)</h1>
+
+ <pre class="medium"><code>package Person;
+
+<span class="highlight">use MooseX::Method::Signatures;</span>
+
+<span class="highlight">method work ( ArrayRef[Task] :$tasks,
+ Bool :$can_rest = 0 )</span> {
+ my $self = shift;
+
+ ...
+}</code></pre>
+
+<div class="slide">
<h1>Digression: The Type Registry</h1>
<ul>
</div>
<div class="slide">
- <h1>Fix #1</h1>
+ <h1>Namespace Fix</h1>
<ul>
<li>Use some sort of pseudo-namespacing scheme</li>
from 'Int',
via { [ $_ ] };</code></pre>
</div>
-
<div class="slide">
- <h1>Coercion Examples</h1>
+ <h1>Namespace Fix Pros and Cons</h1>
- <pre><code>subtype 'My::DateTime',
- as class_type 'DateTime';
+ <ul>
+ <li><span class="right">Relatively simple</span></li>
+ <li><span class="right">Already built into Moose</span></li>
+ <li><span class="wrong">Conflates type and module namespaces</span></li>
+ <li><span class="wrong">Type names are strings, so typos are easy to make and may be hard to find</span></li>
+ </ul>
+</div>
-coerce 'My::DateTime',
- from 'HashRef',
- via { DateTime->new( %{$_} ) };
+<div class="slide">
+ <h1>MooseX::Types</h1>
-coerce 'My::DateTime',
- from 'Int',
- via { DateTime->from_epoch(
- epoch => $_ ) };</code></pre>
+ <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 class="slide">
+ <h1>MooseX::Types</h1>
<ul>
- <li>Using a coercion to inflate a value</li>
+ <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 externally are short</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>Coercion Examples</h1>
+ <h1>MooseX::Types Pros and Cons</h1>
- <pre><code>coerce 'ArrayRef[Int]',
- from 'Int',
- via { [ $_ ] };</code></pre>
+ <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 gets types 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>Coerce instead of a union like <code style="white-space: nowrap">Int | ArrayRef[Int]</code></li>
+ <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>
projects / gitmo/moose-presentations.git / commitdiff