Re: Function pointer casting

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#822

From: David Phillip Oster
Date: Mon, 02 Jun 2003 16:24

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In article <3EDB6B20.2000804@lgl.kos.net>,
 Edward Chew <ekc-noreply@lgl.kos.net> wrote:

>      if(static_cast<void*>(LibraryInitFunction) ==
>         static_cast<void*>(kUnresolvedCFragSymbolAddress)
>         )
>           reportLibraryUnavailable();
> 
> This seems to work fine, but now I am told it is illegal as well.  What 
> would be the proper test in that case?

#define kUnresolvedCFragSymbolAddress \
      static_cast<int>(kUnresolvedCFragSymbolAddress)

      if(LibraryInitFunction == kUnresolvedCFragSymbolAddress){
      }

Discussion: It is always legal to compare a pointer of any type to zero.
(int Zero is special this way. (Long zero ( 0L ) is not.))
In this context, a bare zero would be misleading. We give zero a 
symbolic name, like NULL and noErr are symbolic names for zero, and you
use the correct one, depending on a context, as an aid to those who
will read your source code in the future.

Apple mistakenly defined kUnresolvedCFragSymbolAddress as 0 in an enum,
rather than a #define, which is OK for C but not for C++. The #define
definition overrides the enum definition. A bug report with Apple should
be filed on this.

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References: <3ED6734A.6080600@lgl.kos.net> <mwron-5286CB.09413702062003@enews.newsguy.com> <3EDB6B20.2000804@lgl.kos.net>

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From: David Phillip Oster <oster@ieee.org>
Newsgroups: comp.sys.mac.programmer.codewarrior,codewarrior.mac
Subject: Re: Function pointer casting
Organization: http://www.TurboZen.com
References: <3ED6734A.6080600@lgl.kos.net> <mwron-5286CB.09413702062003@enews.newsguy.com> <3EDB6B20.2000804@lgl.kos.net>
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