nillable deploy resource + nillable LWRP args

introduced nillable_set_or_return so that we can actually set a nil value
on a resource from the DSL.

this fixes the case where you want to do (and we document) setting
symlink_before_migrate to nil on the deploy resource.

to implement this better also moved up the attribute DSL method to the
base Chef::Resource class.

all LWRP resources are now nillable as well.

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/chef/resource.rb b/lib/chef/resource.rb
index ea220b6c70..2df73a52e8 100644
--- a/lib/chef/resource.rb
+++ b/lib/chef/resource.rb
@@ -997,6 +997,15 @@ class Chef
     end
 
     #
+    # DSL method used to define attribute on a resource wrapping params_validate
+    #
+    def self.attribute(attr_name, validation_opts={})
+      define_method(attr_name) do |arg=NULL_ARG|
+        nillable_set_or_return(attr_name.to_sym, arg, validation_opts)
+      end
+    end
+
+    #
     # The cookbook in which this Resource was defined (if any).
     #
     # @return Chef::CookbookVersion The cookbook in which this Resource was defined.