[Q] macro calls macro which calls function why?

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Article #49742

#49742

From: Kai Harrekilde-Petersen
Date: Thu, 09 Dec 1993 14:20

17 lines
1162 bytes

I'm looking on how to implement a `va_assert()' macro, ie: an assert() with
variable arguments.

I used assert.h from my Linux system as a template. I found that assert is
defined like this:

#define assert(expr) __assert(<something>)
#define __assert(<something> ( ... blah blah blah ... )

Why is such a 'double macro' expansion used? Couldn't I just go the direct
way, like:

#define assert(expr) (expr==0? 0 : (printf(something); abort())


Kai Harrekilde-P.

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From: kaihp@id.dth.dk (Kai Harrekilde-Petersen)
Subject: [Q] macro calls macro which calls function why?
Message-ID: <KAIHP.93Dec9152004@idsun3.id.dth.dk>
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Organization: Department of Computing Science, The Technical University of
 Denmark
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Date: Thu, 9 Dec 1993 14:20:04 GMT
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