From: Dave Rolsky <autarch@urth.org>
Date: Tue, 3 Feb 2009 18:24:50 +0000 (+0000)
Subject: Text tweaks for Roles document
X-Git-Tag: 0.66~7
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=ca426a3ac47c83670f232c34ddb663d283c843bf;p=gitmo%2FMoose.git

Text tweaks for Roles document

Added mention of role exclusion
---

diff --git a/lib/Moose/Manual/Roles.pod b/lib/Moose/Manual/Roles.pod
index 3e7397f..1745cdc 100644
--- a/lib/Moose/Manual/Roles.pod
+++ b/lib/Moose/Manual/Roles.pod
@@ -9,13 +9,14 @@ Moose::Manual::Roles - Roles, an Alternative to Deep Hierarchies and Base Classe
 A role is something that classes do. Usually, a role encapsulates some
 piece of behavior or state that can be shared between classes. It is
 important to understand that I<roles are not classes>. Roles do not
-participate in inheritance, and a role cannot be instantiated.
+participate in inheritance, and a role cannot be instantiated. We
+sometimes say that classes I<consume> roles.
 
 Instead, a role is I<composed> into a class. In practical terms, this
 means that all of the methods and attributes defined in a role are
-added directly to (we sometimes say ("flattened into") the class that
-consumes the role. These attributes and methods then show up in the
-class as if they were defined directly in the class.
+added directly to (we sometimes say "flattened into") the class that
+consumes the role. These attributes and methods then appear as if they
+were defined in the class itself.
 
 Moose roles are similar to mixins or interfaces in other languages.
 
@@ -122,18 +123,14 @@ methods:
 If we try to consume this role in a class that does not have a
 C<break> method, we will get an exception.
 
-Note that attribute-generated accessors do not satisfy the requirement
-that the named method exists. Similarly, a method modifier does not
-satisfy this requirement either. This may change in the future.
-
-You can also see that we added a method modifier on
-C<break>. Basically, we want consuming classes to implement their own
-logic for breaking, but we make sure that the C<is_broken> attribute
-is always set to true when C<break> is called.
+You can see that we added a method modifier on C<break>. We want
+classes that consume this role to implement their own logic for
+breaking, but we make sure that the C<is_broken> attribute is always
+set to true when C<break> is called.
 
   package Car
 
-      use Moose;
+  use Moose;
 
   with 'Breakable';
 
@@ -234,6 +231,21 @@ C<Breakable> and C<BreakDancer>, but does not provide a C<break>
 method. If some API expects an object that does one of those roles, it
 probably expects it to implement that method.
 
+In some use cases we might alias and exclude methods from roles, but
+then provide a method of the same name in the class itself.
+
+=head1 ROLE EXCLUSION
+
+A role can say that it cannot be combined with some other role. This
+should be used with great caution, since it limits the re-usability of
+the role.
+
+  package Breakable;
+
+  use Moose::Role;
+
+  excludes 'BreakDancer';
+
 =head1 AUTHOR
 
 Dave Rolsky E<lt>autarch@urth.orgE<gt>