From: "David A. Black" <dblack@...>
Date: 2004-11-13T06:18:55+09:00
Subject: bang methods (was: Re: true? & false?)

Hi --

On Sat, 13 Nov 2004, Michael DeHaan wrote:

> "In ruby there have many methods that names end with '!' like, collect!,
> compact!. I was so used to that '!' means its return the object after
> 'affect' and without '!' return the part of the object that was
> affected."
> 
> The exclamation actually means the operation is destructive and
> forever changes the contents of the calling object.   It doesn't have
> anything to do with the return codes.   It's a very nice convention.

Bang (!) methods don't have to be destructive; the ! basically means
"dangerous operation -- be careful!"  So there can be non-destructive
methods with ! (like exit!), and destructive methods without it (like
Array#pop).  A lot of destructive methods are also bang-methods, but
there's no direct correlation.  

What this means, in Matz's words, is:  "Every bang method has non-bang
(i.e. safer) counterpart.  You can totally forget about bang methods
at first."  


David

-- 
David A. Black
dblack@wobblini.net