From: dblack@...
Date: 2006-01-09T23:57:11+09:00
Subject: Re: use of "return"

Hi --

On Mon, 9 Jan 2006, SB wrote:

> This is a total newbie question, but I'd like to know how "return" is
> specifically used in ruby.  From my understanding, it can be avoided in a
> lot of cases since ruby returns the last value by default.
>
> However, some of the code in the Rails stuff I'm looking at has "return" and
> I was wondering if this "return" is necessary or just the individual
> programmer's style (maybe carried over from other languages).
>
> Sorry, I'm vague but I would like to know how "return" is effectively used
> in ruby if at all.
>
> Here's a code snippet from the SaltedHash Engine
>
>
>    def new_security_token(hours = nil)
>      write_attribute('security_token', AuthenticatedUser.hashed(
> self.salted_password + Time.now.to_i.to_s + rand.to_s))
>      write_attribute('token_expiry', Time.at(Time.now.to_i +
> token_lifetime(hours)))
>      update_without_callbacks
>      return self.security_token

Programmer's individual style.  You could replace that line with:

   security_token

"self" as receiver would be implied, and since it's the last
expression evaluated, it would be the return value of the method.

>    end
>
>
> or this:
>
>      def authenticate(login, pass)
>        u = find(:first, :conditions => ["login = ? AND verified = 1 AND
> deleted = 0", login])
>        return nil if u.nil?

A return in mid-method needs "return".  You could avoid it by
rewriting the end of the method like this:

   if u.nil?
     nil
   else
     other code
   end

But the "return nil if u.nil?" thing both terminates the method and
provides a visual cue that u being nil is a terminal condition.  So
it's partly style, but once you decide to do a mid-method return, you
have to use "return".


David

-- 
David A. Black
dblack@wobblini.net

"Ruby for Rails", from Manning Publications, coming April 2006!
http://www.manning.com/books/black