From: Devin Mullins <twifkak@...>
Date: 2005-12-20T14:57:18+09:00
Subject: Re: is there a way to use a proc like a method?

BTW, a more common way in the Ruby world to do the sort of thing it 
seems you're after is this:

class A
 attr_accessor :av
 def do(mproc)
  mproc.call(self)
 end
end

a = proc {|obj| obj.av = 111}

I see two advantages of that:
- You don't break encapsulation, and thus get complete control over your 
class's interaction with client code.
- The Proc created in the client code gets to refer to its own instance 
variables and methods.

And, yes, I agree with the other comments, too. So, here's my new version:

class A
  attr_accessor :av
  def initialize
    @av = 10
  end
  def do
    yield self
  end
end

b=A.new
b.do {|obj| obj.av = 111}
b.av #=> 111
a = lambda {|obj| obj.av = 112}
b.do &a
b.av #=> 112

Of course, in this simple example, you could just drop the 'def 
do...end', and say:

b = A.new
b.av = 111
b.av #=> 111

But I'm guessing that's not what you're after.

Devin

Ross Bamford wrote:

> On Mon, 19 Dec 2005 20:50:44 -0000, hochherz  
> <hochherz@informatik.hu-berlin.de> wrote:
>
>> is there a way to use a proc like a method?
>>
>> like:
>>
>> class A
>>    def initialize
>>      @av=10;
>>    end
>>    def do(mproc)
>>      mproc.call();
>>    end
>>    def rt()
>>      @av;
>>    end
>> end
>>
>>
>> a=proc{@av=111} #something different
>> b=A.new
>> b.do(a)
>> b.rt #return -> 111
>>
>> is it possible by makeing subclass of proc to do this?
>
>
> Maybe use:
>
>     def do(mproc)
>       instance_eval &mproc
>     end
>
> instead of 'call'
>