From: Robert Klemme <shortcutter@...>
Date: 2007-07-27T15:32:34+09:00
Subject: Re: How to pass arguments by reference in a function

2007/7/27, ashishwave <ashishwave@gmail.com>:
> if i pass arguments in a function then they get passed by value. how
> to get it passed by reference.

You can't.  There are some solutions to this depending on situation:

1. inplace modification of arguments (Strings, Arrays, Hashes - all
sorts of containers)

2. multiple return values

3. work with instance variables

Generally in my experience it's not needed.

> For example: if i want to swrite my own swap function (not using
> multiple assignment syntax a,b=b,a) just for example example, how to
> implement that in ruby

irb(main):001:0> def swap(a,b) return b,a end
=> nil
irb(main):002:0> x,y=1,2
=> [1, 2]
irb(main):003:0> x,y = swap x,y
=> [2, 1]
irb(main):004:0> x
=> 2
irb(main):005:0> y
=> 1

But in reality you would just do

x,y = y,x

Kind regards

robert