From: Matthew Smillie <M.B.Smillie@...>
Date: 2006-07-20T21:42:12+09:00
Subject: Re: return statement where it is usefull ?

On Jul 20, 2006, at 12:30, Yvon Thoraval wrote:

>
> Le 20 juil. 06 � 13:16, Julian 'Julik' Tarkhanov a �crit :
>
>> As for your method, why not use a conditional assignment?  
>> Array#index returns nil when the element is not in the
>> array, so you can get a nil and suppress it with -1.
>>
>> def get_server_index(server)
>>  self.servers.index(server) || -1
>> end
>
> thanks very much, much more rubyish ;-)

Well, as long as we're talking about Rubyish, then -1 is probably not  
the best choice as an indicator of failure, nil would be preferred.

One of the reasons for this is that -1 is a valid array index in  
Ruby, while in the programmer's mind, -1 means failure.  This sort of  
disagreement can lead to some very annoying errors:

servers[some_index].do_something_important

If some_index is nil, you get an immediate error.  If it's -1, then  
you would actually perform the operation, but on an unexpected  
object, which is potentially catastrophic.  Tracking down answers to  
"how did this data get corrupted?" is a vastly unrewarding task.

Obviously, this may not be an issue in your particular code, but it  
is something to watch out for.

matthew smillie.