Is there a way to use a proc like a method?

ruby-talk
1

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?

2

hochherz schrieb:

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?

   class A
     def do(mproc)
       instance_eval(&mproc)
     end
   end

Regards,
Pit

3

Maybe use:

     def do(mproc)
       instance_eval &mproc
     end

instead of 'call'

···

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?

--
Ross Bamford - rosco@roscopeco.remove.co.uk

4

You could also do something like this:

a=proc{@av=111} #something different
a.bind(b).call

-Jeff

···

On Tue, Dec 20, 2005 at 05:57:47AM +0900, hochherz 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?

5

But apparently this doesn't work in practice, scratch that, hehe.

···

On Tue, Dec 20, 2005 at 06:58:33AM +0900, Jeffrey Moss wrote:

You could also do something like this:

a=proc{@av=111} #something different
a.bind(b).call

-Jeff

On Tue, Dec 20, 2005 at 05:57:47AM +0900, hochherz 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?
>

6

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'