[Moose-commits] r7614 - in Moose/trunk: lib/Moose/Cookbook/Basics t/000_recipes/basics

[autarch at code2.0beta.co.uk]

Author: autarch
Date: 2009-02-11 11:31:37 -0800 (Wed, 11 Feb 2009)
New Revision: 7614

Modified:
   Moose/trunk/lib/Moose/Cookbook/Basics/Recipe5.pod
   Moose/trunk/t/000_recipes/basics/005_coercion.t
Log:
Don't define a coercion directly to a class like URI. Make a subtype
and coerce that instead.

Modified: Moose/trunk/lib/Moose/Cookbook/Basics/Recipe5.pod
===================================================================
--- Moose/trunk/lib/Moose/Cookbook/Basics/Recipe5.pod	2009-02-11 19:19:54 UTC (rev 7613)
+++ Moose/trunk/lib/Moose/Cookbook/Basics/Recipe5.pod	2009-02-11 19:31:37 UTC (rev 7614)
@@ -15,17 +15,17 @@
   use Params::Coerce ();
   use URI            ();
 
-  class_type('HTTP::Headers');
+  subtype 'My.HTTP::Headers' => as class_type('HTTP::Headers');
 
-  coerce 'HTTP::Headers'
+  coerce 'My.HTTP::Headers'
       => from 'ArrayRef'
           => via { HTTP::Headers->new( @{$_} ) }
       => from 'HashRef'
           => via { HTTP::Headers->new( %{$_} ) };
 
-  class_type('URI');
+  subtype 'My.URI' => as class_type('HTTP::Headers');
 
-  coerce 'URI'
+  coerce 'My.URI'
       => from 'Object'
           => via { $_->isa('URI')
                    ? $_
@@ -37,13 +37,13 @@
       => as 'Str'
       => where { /^HTTP\/[0-9]\.[0-9]$/ };
 
-  has 'base' => ( is => 'rw', isa => 'URI', coerce => 1 );
-  has 'uri'  => ( is => 'rw', isa => 'URI', coerce => 1 );
+  has 'base' => ( is => 'rw', isa => 'My.URI', coerce => 1 );
+  has 'uri'  => ( is => 'rw', isa => 'My.URI', coerce => 1 );
   has 'method'   => ( is => 'rw', isa => 'Str' );
   has 'protocol' => ( is => 'rw', isa => 'Protocol' );
   has 'headers'  => (
       is      => 'rw',
-      isa     => 'HTTP::Headers',
+      isa     => 'My.HTTP::Headers',
       coerce  => 1,
       default => sub { HTTP::Headers->new }
   );
@@ -61,11 +61,17 @@
 
 First, we create the subtype to which we will coerce the other types:
 
-  class_type('HTTP::Headers');
+  subtype 'My.HTTP::Headers' => as class_type('HTTP::Headers');
 
-The C<class_type> sugar function is simply a shortcut for something
-like this:
+We are creating a subtype rather than using C<HTTP::Headers> as a type
+directly. The reason we do this is coercions are global, and a
+coercion defined for C<HTTP::Headers> in our C<Request> class would
+then be defined for I<all> Moose-using classes in the current Perl
+interpreter. It's a L<best practice|Moose::Manual::BestPractices> to
+avoid this sort of namespace pollution.
 
+The C<class_type> sugar function is simply a shortcut for this:
+
   subtype 'HTTP::Headers'
       => as 'Object'
       => where { $_->isa('HTTP::Headers') };
@@ -92,7 +98,7 @@
 instance, and just do the right thing. This is exactly what coercion
 is for:
 
-  coerce 'HTTP::Headers'
+  coerce 'My.HTTP::Headers'
       => from 'ArrayRef'
           => via { HTTP::Headers->new( @{$_} ) }
       => from 'HashRef'
@@ -108,7 +114,7 @@
 
   has 'headers' => (
       is      => 'rw',
-      isa     => 'Header',
+      isa     => 'My.HTTP::Headers',
       coerce  => 1,
       default => sub { HTTP::Headers->new }
   );
@@ -131,11 +137,11 @@
 Once again, we need to declare a class type for our non-Moose L<URI>
 class:
 
-  class_type('URI');
+  subtype 'My.URI' => as class_type('HTTP::Headers');
 
 Then we define the coercion:
 
-  coerce 'URI'
+  coerce 'My.URI'
       => from 'Object'
           => via { $_->isa('URI')
                    ? $_
@@ -158,8 +164,8 @@
 
 Finally, we need to make sure our attributes enable coercion.
 
-  has 'base' => ( is => 'rw', isa => 'URI', coerce => 1 );
-  has 'uri'  => ( is => 'rw', isa => 'URI', coerce => 1 );
+  has 'base' => ( is => 'rw', isa => 'My.URI', coerce => 1 );
+  has 'uri'  => ( is => 'rw', isa => 'My.URI', coerce => 1 );
 
 Re-using the coercion lets us enforce a consistent API across multiple
 attributes.

Modified: Moose/trunk/t/000_recipes/basics/005_coercion.t
===================================================================
--- Moose/trunk/t/000_recipes/basics/005_coercion.t	2009-02-11 19:19:54 UTC (rev 7613)
+++ Moose/trunk/t/000_recipes/basics/005_coercion.t	2009-02-11 19:31:37 UTC (rev 7614)
@@ -22,17 +22,17 @@
     use Params::Coerce ();
     use URI            ();
 
-    class_type('HTTP::Headers');
+    subtype 'My.HTTP::Headers' => as class_type('HTTP::Headers');
 
-    coerce 'HTTP::Headers'
+    coerce 'My.HTTP::Headers'
         => from 'ArrayRef'
             => via { HTTP::Headers->new( @{$_} ) }
         => from 'HashRef'
             => via { HTTP::Headers->new( %{$_} ) };
 
-    class_type('URI');
+    subtype 'My.URI' => as class_type('HTTP::Headers');
 
-    coerce 'URI'
+    coerce 'My.URI'
         => from 'Object'
             => via { $_->isa('URI')
                      ? $_
@@ -44,13 +44,13 @@
         => as 'Str'
         => where { /^HTTP\/[0-9]\.[0-9]$/ };
 
-    has 'base' => ( is => 'rw', isa => 'URI', coerce => 1 );
-    has 'uri'  => ( is => 'rw', isa => 'URI', coerce => 1 );
+    has 'base' => ( is => 'rw', isa => 'My.URI', coerce => 1 );
+    has 'uri'  => ( is => 'rw', isa => 'My.URI', coerce => 1 );
     has 'method'   => ( is => 'rw', isa => 'Str' );
     has 'protocol' => ( is => 'rw', isa => 'Protocol' );
     has 'headers'  => (
         is      => 'rw',
-        isa     => 'HTTP::Headers',
+        isa     => 'My.HTTP::Headers',
         coerce  => 1,
         default => sub { HTTP::Headers->new }
     );