Re: nil messaging? Is it safe?
Re: nil messaging? Is it safe?
On Thu, Sep 26, 2002 at 09:39:21PM +0200, Gerben Wierda wrote:
>
Now, I do not understand this. How can the compiler or the runtime
>
system know what the message will return? After all, nil has no class,
>
so there is no way of knowing the signature of the message (that is, the
>
return value).
The compiler keeps track of all available selectors (for all known
classes); for a given selector there can be only one return type. If
the selector is unknown, I think you can only get an object/nil return
type, but I'm not sure.
>
I was under the impression that any message sent to nil will just return
>
nil and that's it. No harm done. But both statements above do suggest
>
something else is going on. So: is it safe to send messages to nil? What
>
does the runtime system exactly do with messages like that?
Nothing, just be careful if you use the return value and it's not an
object/pointer type.
--
=Nicholas Riley <email@hidden> | <
http://www.uiuc.edu/ph/www/njriley>
Pablo Research Group, Department of Computer Science and
Medical Scholars Program, University of Illinois at Urbana-Champaign
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