DumbDelegator

Ruby provides the delegate standard library. However, we found that it is not appropriate for many use cases that require nearly every call to be proxied.

For instance, Rails uses #class and #instance_of? to introspect on model classes when generating forms and URL helpers. These methods are not forwarded when using Delegator or SimpleDelegator.

“by require ‘delegate’

class MyAwesomeClass # … end

o = MyAwesomeClass.new d = SimpleDelegator.new(o)

d.class # => SimpleDelegator d.is_a? MyAwesomeClass # => false

“

DumbDelegator, on the other hand, forwards almost ALL the things:

“by require ‘dumb_delegator’

class MyAwesomeClass # … end

o = MyAwesomeClass.new d = DumbDelegator.new(o)

d.class # => MyAwesomeClass d.is_a? MyAwesomeClass # => true

“

Usage

Rails Model Decorator

There are many decorator implementations in Ruby. One of the simplest is “SimpleDelegator + super + getobj,” but it has the drawback of confusing Rails. It is necessary to redefine class. We’ve also observed the need to redefine instance_of? for URL helpers.

With DumbDelegator, there’s not a need for this hackery because nearly every possible method is delegated:

“by require ‘dumb_delegator’

class Coffee def cost 2 end

def origin ‘Colombia’ end end

class Milk < DumbDelegator def cost super + 0.4 end end

class Sugar < DumbDelegator def cost super + 0.2 end end

coffee = Coffee.new Sugar.new(Milk.new(coffee)).cost # 2.6 Sugar.new(Sugar.new(coffee)).cost # 2.4 Milk.new(coffee).origin # Colombia Sugar.new(Milk.new(coffee)).class # Coffee

“

Installation

Add this line to your application’s Gemfile:

gem 'dumb_delegator'

And then execute:

$ bundle

Or install it yourself as:

$ gem install dumb_delegator

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

Contribution Ideas/Needs

1. Ruby 1.8 support (use the blankslate gem?)