Re: what's wrong with this use of the index to clean a list?

[jalex]

Paul E. Johnson writes:

> Here is what I don't get:  what does the processing inside the loop do
> when it gets passed a nil member value?  Suppose inside that for loop
> there is a command
>    [member doSomething];
> ?
> Should the program be testing every "member" to see if it is not nil? 
> Without doing that, I suppose I would expect a crash at run time saying
> "nil does not respond to doSomething"?  But I have not seen such a
> crash. 

If my understanding of the Objective-C language is correct, sending
messages to nil doesn't cause the program to crash.  On the contrary,
the message is ignored and the program continues on its merry way.
This is a "feature" of the language.

So, although sending messages to nil doesn't hurt anything,
it is almost always a sign that something else is awry in the
program.  I bet, though, that someone else could cook up an example 
showing the Great Benefits of being able to send messages to nil
without having the program crash.


Cheers,

Jason






                  ==================================
   Swarm-Support is for discussion of the technical details of the day
   to day usage of Swarm.  For list administration needs (esp.
   [un]subscribing), please send a message to <address@hidden>
   with "help" in the body of the message.