Variable length arg lists for macros
Chris Torek
chris at mimsy.UUCP
Thu Sep 15 23:50:48 AEST 1988
In article <362 at island.uu.net> walker at island.uu.net (Richard Walker)
suggests that
>... macros which expand into code with flow control
>should be formed such that the semicolon cleanly terminates
>the flow, e.g.:
>
>#define COMPLEX_MACRO(foo) (if(SOME_TEST(foo)) {statements;}else)
This works (after correcting the syntax), but I recommend instead
#define MAC() if (!(normal_test)) /*void*/; else mac_statement
or, if you need {}s,
#define MAC() do { mac_statements } while (0)
These have the advantage over the one above that
MAC() /* missing semicolon */
next_stmt;
produces a syntax error, rather than code that reads
if (some_test) { statements; } else next_stmt;
--
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain: chris at mimsy.umd.edu Path: uunet!mimsy!chris
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