From: ES <ruby-ml@...>
Date: 2005-05-18T13:14:32+09:00
Subject: Re: Help with facade pattern

Daniel Berger wrote:
> Hi all,
> 
> Well, I *think* it's the facade pattern.  Anyway, I'm trying to do
> something like this:
> 
> class Foo < String
>    def method_a
>       Bar.method_a(self)
>    end
>    def method_b
>       Bar.method_b(self)
>    end
> end
> 
> This is easy enough to do by hand for a few methods, but what if I have
> many methods from Bar I want to use?
> 
> I thought maybe there was a trick with Forwardable I could use, but I
> don't see how.  Any ideas on how to shortcut this?

You left too quick :) You are looking at something like this:

class Class
   def forward(mod, *methods)
     methods.each do |method|
       # Substitute mod with const_get(mod) if you want to use :ModName
       define_method(method) {|| mod.send(method, self)}
     end
   end
end

class A
   def A.foo(x)
     puts "A.foo: #{x}"
   end
end

class B
   forward A, :foo
end

B.new.foo  # => A.foo

> Regards,
> 
> Dan

E

-- 
template<typename duck>
void quack(duck& d) { d.quack(); }