From: Karen Etheridge <ether@cpan.org>
Date: Fri, 25 Feb 2011 18:03:25 +0000 (-0800)
Subject: add example for combining an initializer with a writer - basically the same code... 
X-Git-Tag: 1.9903~6
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=44c5aa3295358c7f0d33996d80f53f49c2f0fc2a;p=gitmo%2FMoose.git

add example for combining an initializer with a writer - basically the same code as in stackoverflow.com/q/5116788/40468
---

diff --git a/lib/Class/MOP/Attribute.pm b/lib/Class/MOP/Attribute.pm
index 1603ed5..808cb0f 100644
--- a/lib/Class/MOP/Attribute.pm
+++ b/lib/Class/MOP/Attribute.pm
@@ -617,8 +617,31 @@ attribute initialization use the writer:
       )
   );
 
-Your writer will need to examine C<@_> and determine under which
-context it is being called.
+Your writer (actually, a wrapper around the writer, using
+L<method modifications|Moose::Manual::MethodModifiers>) will need to examine
+C<@_> and determine under which
+context it is being called:
+
+  around 'some_attr' => sub {
+      my $orig = shift;
+      my $self = shift;
+      # $value is not defined if being called as a reader
+      # $setter and $attr are only defined if being called as an initializer
+      my ($value, $setter, $attr) = @_;
+
+      # the reader behaves normally
+      return $self->$orig if not @_;
+
+      # mutate $value as desired
+      # $value = <something($value);
+
+      # if called as an initializer, set the value and we're done
+      return $setter->($row) if $setter;
+
+      # otherwise, call the real writer with the new value
+      $self->$orig($row);
+  };
+
 
 =back