From: "Rubén Medellín" <CHubas7@...>
Date: 2009-01-29T01:42:47+09:00
Subject: Re: function inside a function

In ruby, function_a is a method call (with no arguments), and as a
call, it gets evaluated to whatever that function returns. If you
wanted to grab the function as a "pure function", you'd use lambdas or
Procs like Jesús pointed.

In other words:

function_a = Proc.new {|x| ..do something with x... }

returns a functional object. You can then call the method with
function_a.call (aliased [])

see http://www.ruby-doc.org/core/classes/Proc.html for details on Proc
objects


Greetings

On Jan 28, 9:49 am, Jason Lillywhite <jason.lillywh...@gmail.com>
wrote:
> I have a question about the timing of function evaluations in this case:
>
> def function_a(x = 1)
>   x**2 + x
> end
>
> def function_b(any_function)
>   y = 4 + 5 #this would actually be more complex
>   function_a(y)
> end
>
> puts function_b(function_a)
>
> I found that function_a(x = 1) is evaluated first, then
> function_b(function_a). I found that 'def function_a(x = nil) returns an
> error. Why does function_a need to be evaluated before it is called as
> an argument in function_b?
>
> PS - the reason I am writing things this way is to make function_b
> accept any function (within reason).
> --
> Posted viahttp://www.ruby-forum.com/.