(#6978) Add before and after decorators to actions from options.

Options can now add before_action and after_action blocks; these are invoked
before or after any action is invoked on the face.  This allows these options
to declare common behaviour and have it automatically applied to the actions
invoked.

Option hooks have no defined order of invocation: they will run in a
completely random order.  Where there are dependencies they should be on the
value of the options hash passed to the invocation, not on side-effects of the
other invocations.

You are not able to influence the arguments, options, or calling of the action
body in a before or after decorator.  This is by design.

The invocation passes to the hook:

 1. The action object representing this action.
 2. The arguments to the action, as an array.
 3. The options for the action, as a hash.

Paired-With: Max Martin <max@puppetlabs.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/lib/puppet/interface.rb b/lib/puppet/interface.rb
index 6570ebe46..5e9355061 100644
--- a/lib/puppet/interface.rb
+++ b/lib/puppet/interface.rb
@@ -117,4 +117,43 @@ class Puppet::Interface
   def to_s
     "Puppet::Face[#{name.inspect}, #{version.inspect}]"
   end
+
+  ########################################################################
+  # Action decoration, whee!  You are not expected to care about this code,
+  # which exists to support face building and construction.  I marked these
+  # private because the implementation is crude and ugly, and I don't yet know
+  # enough to work out how to make it clean.
+  #
+  # Once we have established that these methods will likely change radically,
+  # to be unrecognizable in the final outcome.  At which point we will throw
+  # all this away, replace it with something nice, and work out if we should
+  # be making this visible to the outside world... --daniel 2011-04-14
+  private
+  def __invoke_decorations(type, action, passed_args = [], passed_options = {})
+    [:before, :after].member?(type) or fail "unknown decoration type #{type}"
+
+    # Collect the decoration methods matching our pass.
+    methods = action.options.select do |name|
+      passed_options.has_key? name
+    end.map do |name|
+      action.get_option(name).__decoration_name(type)
+    end
+
+    methods.each do |hook|
+      begin
+        respond_to? hook and self.__send__(hook, action, passed_args, passed_options)
+      rescue => e
+        Puppet.warning("invoking #{action} #{type} hook: #{e}")
+      end
+    end
+  end
+
+  def __decorate(type, name, proc)
+    meta_def(name, &proc)
+    method(name).unbind
+  end
+  def self.__decorate(type, name, proc)
+    define_method(name, proc)
+    instance_method(name)
+  end
 end