From: "Simon Kröger" <SimonKroeger@...>
Date: 2005-08-09T06:26:42+09:00
Subject: Re: Proc as a parameter in a class

Yannick Turgeon wrote:

> Hello all,
> 
> I'm currently playing with proc and code block as parameter trying to
> learn this aspect. Bellow is some code: three sections. The first one
> explain by itself what I whant to do, except that I would like to use
> classes. The second is the same in my point of view than the first one
> and using a class... but it's now doing what I was expecting. The third
> one is working but I don' understand why it should be like this.
> Anybody can give me the reason?
> 
> Thanks.
> 
> Yannick
> 
> ---------------------------------
> ##### FIRST SECTION #####
> puts "First section"
> 
> def fn(text)
>     return proc{|factor| puts text * factor}
> end
> 
> f = fn("Joe ")
> f.call(3)       #It prints "Joe Joe Joe ", as expected.
> 
> 
> 
> 
> ##### SECOND SECTION #####
> puts "Second section"
> 
> class Bob
>     def initialize(factor, &block)
>         @factor = factor
>         @action = block
>     end
> 
>     def run
>         @action.call(@factor)
>     end
> end
> 
> b = Bob.new(3){f}
> b.run         #It prints nothing [b.run return the function returned by
> fn()]
> 
> 
> 
> ##### THIRD SECTION #####
> puts "Third section"
> 
> #Redefine run()
> class Bob
>     def run
>         @action.call.call(@factor)      #Why should I call "call"
> twice. Isn't @action supposed to be the function returned by fn()?
>     end
> end
> 
> b = Bob.new(3){f}
> b.run()         #It prints "Joe Joe Joe ".
> ---------------------------------
> 
> 
> 

@action is the block.
@action.call excutes the block which returns f
f.call prints "Joe Joe Joe "

cheers

Simon