nil messaging? Is it safe?
nil messaging? Is it safe?
- Subject: nil messaging? Is it safe?
- From: Gerben Wierda <email@hidden>
- Date: Thu, 26 Sep 2002 21:39:21 +0200
I did not see the original message, but
You certainly CAN send messages to nil! I do it all the time. It sends
the
message up the responder chain.
"up the responder chain"?? According to the Obj-C manual sending a
message to nil
"is valid as long as the message returns an object; if it does, a
message sent to nil will return nil. If the message sent to nil returns
anything other than an object, the return value is undefined"
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).
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?
Thanks,
G
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