From: Yannick Turgeon <vendredi5h@...>
Date: 2005-08-09T06:21:08+09:00
Subject: Proc as a parameter in a class

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 ".
---------------------------------