Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!versatc!leadsv!esl!dml
From: dml@esl.UUCP (Denis Lynch)
Newsgroups: comp.sys.next
Subject: Re: Deferred methods and strong typing
Message-ID: <934@esl.UUCP>
Date: 8 Jul 89 03:21:15 GMT
References: <130007@gore.com> <3312@stpstn.UUCP>
Reply-To: dml@esl.UUCP (Denis Lynch)
Organization: ESL, Inc., Sunnyvale, CA.
Lines: 32

In article <3312@stpstn.UUCP> andyn@stepstone.com (Andy Novobilski) writes:
>
>Correct type information can be given to the compiler by:
>
>1) Typing the method:
>   [(B *)anInstanceOfB someMethod];
>
>2) Declaring anInstanceOfB to be type B:
>   B *anInstanceOfB;

Isn't it true that the warning is generated because of the *declaration* of
someMethod, not its use? (Of course the run-time problem happens because of
the use).

This seems to be pretty much required because of the *possibility* of
dynamic binding: the compiler needs to be able to figure out what someMethod
will return under any circumstances, especially since common usage is to
type everything as id.

(I know I could go try this on my machine, but it's in another room...)

This seems to be one of the prices to be paid for using dynamic binding in
a language that doesn't fully support it. In Smalltalk there is no such
problem, since someMethod will return whatever it wants. In C we don't have
that luxury.


-- 
Denis Lynch                          
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