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Diffstat (limited to 'lib/puppet/interface/action.rb')
| -rw-r--r-- | lib/puppet/interface/action.rb | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/lib/puppet/interface/action.rb b/lib/puppet/interface/action.rb new file mode 100644 index 000000000..e4a37a1f7 --- /dev/null +++ b/lib/puppet/interface/action.rb @@ -0,0 +1,119 @@ +# -*- coding: utf-8 -*- +require 'puppet/interface' +require 'puppet/interface/option' + +class Puppet::Interface::Action + def initialize(face, name, attrs = {}) + raise "#{name.inspect} is an invalid action name" unless name.to_s =~ /^[a-z]\w*$/ + @face = face + @name = name.to_sym + @options = {} + attrs.each do |k, v| send("#{k}=", v) end + end + + attr_reader :name + def to_s() "#{@face}##{@name}" end + + + # Initially, this was defined to allow the @action.invoke pattern, which is + # a very natural way to invoke behaviour given our introspection + # capabilities. Heck, our initial plan was to have the faces delegate to + # the action object for invocation and all. + # + # It turns out that we have a binding problem to solve: @face was bound to + # the parent class, not the subclass instance, and we don't pass the + # appropriate context or change the binding enough to make this work. + # + # We could hack around it, by either mandating that you pass the context in + # to invoke, or try to get the binding right, but that has probably got + # subtleties that we don't instantly think of – especially around threads. + # + # So, we are pulling this method for now, and will return it to life when we + # have the time to resolve the problem. For now, you should replace... + # + # @action = @face.get_action(name) + # @action.invoke(arg1, arg2, arg3) + # + # ...with... + # + # @action = @face.get_action(name) + # @face.send(@action.name, arg1, arg2, arg3) + # + # I understand that is somewhat cumbersome, but it functions as desired. + # --daniel 2011-03-31 + # + # PS: This code is left present, but commented, to support this chunk of + # documentation, for the benefit of the reader. + # + # def invoke(*args, &block) + # @face.send(name, *args, &block) + # end + + def when_invoked=(block) + # We need to build an instance method as a wrapper, using normal code, to + # be able to expose argument defaulting between the caller and definer in + # the Ruby API. An extra method is, sadly, required for Ruby 1.8 to work. + # + # In future this also gives us a place to hook in additional behaviour + # such as calling out to the action instance to validate and coerce + # parameters, which avoids any exciting context switching and all. + # + # Hopefully we can improve this when we finally shuffle off the last of + # Ruby 1.8 support, but that looks to be a few "enterprise" release eras + # away, so we are pretty stuck with this for now. + # + # Patches to make this work more nicely with Ruby 1.9 using runtime + # version checking and all are welcome, but they can't actually help if + # the results are not totally hidden away in here. + # + # Incidentally, we though about vendoring evil-ruby and actually adjusting + # the internal C structure implementation details under the hood to make + # this stuff work, because it would have been cleaner. Which gives you an + # idea how motivated we were to make this cleaner. Sorry. --daniel 2011-03-31 + + internal_name = "#{@name} implementation, required on Ruby 1.8".to_sym + file = __FILE__ + "+eval" + line = __LINE__ + 1 + wrapper = "def #{@name}(*args, &block) + args << {} unless args.last.is_a? Hash + args << block if block_given? + self.__send__(#{internal_name.inspect}, *args) + end" + + if @face.is_a?(Class) + @face.class_eval do eval wrapper, nil, file, line end + @face.define_method(internal_name, &block) + else + @face.instance_eval do eval wrapper, nil, file, line end + @face.meta_def(internal_name, &block) + end + end + + def add_option(option) + option.aliases.each do |name| + if conflict = get_option(name) then + raise ArgumentError, "Option #{option} conflicts with existing option #{conflict}" + elsif conflict = @face.get_option(name) then + raise ArgumentError, "Option #{option} conflicts with existing option #{conflict} on #{@face}" + end + end + + option.aliases.each do |name| + @options[name] = option + end + + option + end + + def option?(name) + @options.include? name.to_sym + end + + def options + (@options.keys + @face.options).sort + end + + def get_option(name) + @options[name.to_sym] || @face.get_option(name) + end +end |