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module RGen
module Util
module MethodDelegation
class << self
def registerDelegate(delegate, object, method)
method = method.to_sym
createDelegateStore(object)
if object._methodDelegates[method]
object._methodDelegates[method] << delegate
else
object._methodDelegates[method] = [delegate]
createDelegatingMethod(object, method)
end
end
def unregisterDelegate(delegate, object, method)
method = method.to_sym
return unless object.respond_to?(:_methodDelegates)
return unless object._methodDelegates[method]
object._methodDelegates[method].delete(delegate)
if object._methodDelegates[method].empty?
object._methodDelegates[method] = nil
removeDelegatingMethod(object, method)
removeDelegateStore(object)
end
end
private
def createDelegateStore(object)
return if object.respond_to?(:_methodDelegates)
class << object
def _methodDelegates
@_methodDelegates ||= {}
end
end
end
def removeDelegateStore(object)
return unless object.respond_to?(:_methodDelegates)
class << object
remove_method(:_methodDelegates)
end
end
def createDelegatingMethod(object, method)
if hasMethod(object, method)
object.instance_eval <<-END
class << self
alias #{aliasMethodName(method)} #{method}
end
END
end
# define the delegating method
object.instance_eval <<-END
class << self
def #{method}(*args, &block)
@_methodDelegates[:#{method}].each do |d|
catch(:continue) do
return d.#{method}_delegated(self, *args, &block)
end
end
# if aliased method does not exist, we want an exception
#{aliasMethodName(method)}(*args, &block)
end
end
END
end
def removeDelegatingMethod(object, method)
if hasMethod(object, aliasMethodName(method))
# there is an aliased original, restore it
object.instance_eval <<-END
class << self
alias #{method} #{aliasMethodName(method)}
remove_method(:#{aliasMethodName(method)})
end
END
else
# just delete the delegating method
object.instance_eval <<-END
class << self
remove_method(:#{method})
end
END
end
end
def hasMethod(object, method)
# in Ruby 1.9, #methods returns symbols
if object.methods.first.is_a?(Symbol)
method = method.to_sym
else
method = method.to_s
end
object.methods.include?(method)
end
def aliasMethodName(method)
"#{method}_delegate_original"
end
end
end
end
end
|
