From: Jim Freeze <jim@...>
Date: 2002-07-30T21:48:38+09:00
Subject: Procs and scope (function pointers)

Hi:

I have a class that that has several 
procs (function pointers). I would like to 
keep these procs defined as class variables.
Also, I wish the procs to be able to access member
variables. However, I'm not sure this is possible.

I did see some esoteric tricks by Matz in earlier postings
but I did not know if they apply.

Here is a sample of what I want to do:


class Func
  F1 = proc { |x| x }
  F2 = proc { |x| x**2 }
  ...

  def initialize(func)
    case func
      when :F1 then @func = F1
      when :F2 then @func = F2
      ...
      raise "unknown"
  end

  def compute(x)
     @func.call(x)
  end
end

This works, but not if F? accesses an instance  variable or method.
If I move the proc definitions inside the initialization method,
I can get the required binding I need and can call instance methods.

Is there a way to access instance methods/variables and still
keep the function definitions at the class level?

Thanks
-- 
Jim Freeze
If only I had something clever to say for my comment...
~