From: Robert Klemme <bob.news@...>
Date: 2003-07-17T22:36:25+09:00
Subject: Re: callbacks in ruby and using yield in resursion


"Paul" <webmaster@startlinux.co.nz> schrieb im Newsbeitrag
news:1058402958.4573.7.camel@paulsmachine...
> Hi,
>
> How do I pass a ruby function as an argument to another ruby function so
> that it can be used as a callback?

There is no such thing as a function, there are only methods in Ruby.  You
can create Method instances the way Brian showed in his posting.  Another
option is to use a block converted to a Proc:

def fun2( fun, x )
  fun.call( x, x )
end

def add(x,y)
  x+y
end

# Method instance (C) 2003 Brian
fun = method :add
fun2( fun, 10 )

# Proc instance
fun = proc {|x,y| x+y}
fun2( fun, 10 )

You can even curry:

def curry( fun, arg )
  return proc {|x| fun.call(arg, x) }
end

fun = curry( method( :add ), 10 )
fun.call( 5 )

fun = curry( proc {|x,y| x+y}, 10 )
fun.call( 5 )

Regards

    robert