Re: Macro redefinition

From: Ian Collins <ian-news@xxxxxxxxxxx>
Date: Sat, 01 Sep 2007 08:06:05 +1200

Tor Rustad wrote:

I'm implementing a parser, where there is a lot of different data
elements defined. Now instead of hand-coding X defines, and the massive
number of lines needed for table initialization, I decided to generate
this source instead.

So, I basically used this trick:

void gen_source_function(FILE *out)
{
#define EXPAND_DEF(num, name) generate_source_1(out, num, #name)
#include "iso8583_defs"

#define EXPAND_DEF(num, name) generate_source_2(out, num, #name)
#include "iso8583_defs"

}

where the "iso8583_defs" file, did contain a lot of lines like this:

EXPAND_DEF(1, FIELD_NAME);
EXPAND_DEF(2, ANOTHER_FIELD_NAME);

My question is simply, is the above C code allowed?

With the require #unded as explained else thread, it is quite common.

One project I worked on used it extensively, but with hind site, we
found the code hard to maintain, so we dropped the technique and used
code generation from XML instead.

--
Ian Collins.
.

References:
- Macro redefinition
  - From: Tor Rustad

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Re: Macro redefinition
... Now instead of hand-coding X defines, ... number of lines needed for table initialization, ... #define EXPAND_DEF(num, name) generate_source_1 ... forget to #undef EXPAND_DEF before redefining it. ...
(comp.lang.c)
Macro redefinition
... I'm implementing a parser, where there is a lot of different data elements defined. ... Now instead of hand-coding X defines, and the massive number of lines needed for table initialization, I decided to generate this source instead. ... #define EXPAND_DEF(num, name) generate_source_1 ...
(comp.lang.c)