Provides standard layout lookup behavior for method and proc cases

When setting the layout either by referencing a method or supplying a
Proc there is no way to fall back to the default lookup behavior if
desired. This patch allows fallback to the layout lookup behavior when
returning nil from the proc or method.

1 files changed, 9 insertions, 5 deletions

diff --git a/actionpack/lib/abstract_controller/layouts.rb b/actionpack/lib/abstract_controller/layouts.rb
index 91864f2a35..bac994496e 100644
--- a/actionpack/lib/abstract_controller/layouts.rb
+++ b/actionpack/lib/abstract_controller/layouts.rb
@@ -285,10 +285,9 @@ module AbstractController
         remove_possible_method(:_layout)
 
         prefixes    = _implied_layout_name =~ /\blayouts/ ? [] : ["layouts"]
+        default_behavior = "lookup_context.find_all('#{_implied_layout_name}', #{prefixes.inspect}).first || super"
         name_clause = if name
-          <<-RUBY
-            lookup_context.find_all("#{_implied_layout_name}", #{prefixes.inspect}).first || super
-          RUBY
+          default_behavior
         else
           <<-RUBY
             super
@@ -301,6 +300,7 @@ module AbstractController
           when Symbol
             <<-RUBY
               #{_layout}.tap do |layout|
+                return #{default_behavior} if layout.nil?
                 unless layout.is_a?(String) || !layout
                   raise ArgumentError, "Your layout method :#{_layout} returned \#{layout}. It " \
                     "should have returned a String, false, or nil"
@@ -308,8 +308,12 @@ module AbstractController
               end
             RUBY
           when Proc
-              define_method :_layout_from_proc, &_layout
-              _layout.arity == 0 ? "_layout_from_proc" : "_layout_from_proc(self)"
+            define_method :_layout_from_proc, &_layout
+            <<-RUBY
+              result = _layout_from_proc(#{_layout.arity == 0 ? '' : 'self'})
+              return #{default_behavior} if result.nil?
+              result
+            RUBY
           when false
             nil
           when true