From: Phrogz <gavin@...>
Date: 2005-07-20T04:45:55+09:00
Subject: Re: Instance Eval of a Proc

"Ara.T.Howard" <Ara.T.How...@noaa.gov> writes:
[a bunch of snipped examples]

Ara, thanks for helping investigate this. Your C::self_boxed method is
being called with an explicit receiver (C), which is, of course, what
I'm trying to avoid/change using instance_eval.

Two examples from languages with first-class functions:
Lua:
  C = { name='C' }
  function C:show_name( )
    print( self.name )
  end

  b = { name='bob' }
  C.show_name( b )  --> "bob"
  -- Here, 'b' is being passed as the first implicit
  -- 'self' parameter to show_name

JavaScript:
  Array.prototype.show_length = function( ){
    alert( this.length )
  }
  var a = [1,2,3];
  var foo = "I'm a string with a length property";
  a.show_length.call( foo ); //"35"
  //a.show_length looks up the Function instance
  //which has a "call" method that allows you to change
  //the scope of 'this'

I know that Ruby doesn't currently have first-class functions, but I'm
trying to determine if there's a way to do the equivalent of the above.
Is there any way to invoke a method defined on one class within the
scope of an instance of any other class?