Add helper 'for_each_dive()' dive iterator

It's an easy thing to do, but the for-loop ends up being pretty ugly, so
hide it behind the macro.

It would be even prettier with one of the (few) useful C99 features:
local for-loop variables.  However, gcc needs special command line
options, and other compilers may not do it at all. So instead of doing

   #define for_each_dive(_x) \
      for (int _i = 0; ((_x) = get_dive(_i)) != NULL; _i++)

we require that the user declare the index iterator too, and the use
syntax becomes

   for_each_dive(idx, dive) {
	... use idx/dive here ...
   }

And hey, maybe somebody actually will want to use the index, so maybe
that's not all bad.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2012-08-21 15:51:34 -07:00
parent e46688d694
commit 666538ec77
4 changed files with 13 additions and 3 deletions

10
dive.h
View file

@ -295,6 +295,16 @@ static inline struct dive *get_dive(unsigned int nr)
return dive_table.dives[nr];
}
/*
* Iterate over each dive, with the first parameter being the index
* iterator variable, and the second one being the dive one.
*
* I don't think anybody really wants the index, and we could make
* it local to the for-loop, but that would make us requires C99.
*/
#define for_each_dive(_i,_x) \
for ((_i) = 0; ((_x) = get_dive(_i)) != NULL; (_i)++)
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extern void set_filename(const char *filename);