There are two problems with encapsulating that version in my LOOP_OVER_ALL_ELEPHANTS macro. One is that it contains two separate statements, so it breaks syntactic indivisibility in cases like
if (condition)
LOOP_OVER_ALL_ELEPHANTS(elephant) {
/* ... */
}
Admittedly you might reasonably feel that I should just avoid calling the macro in any circumstances like that, which would be a fair enough position, but I note that all the other expansions discussed here (including the evil switch one) do work in that context.
But the other, more important, reason is that it has a declaration in it, and in C90 declarations can't be interleaved with code. (For annoying reasons, the code in which I was using this macro is required to compile cleanly in C90 as well as C99.) So if I put any other statement before calling LOOP_OVER_ALL_ELEPHANTS, the declaration of specialfirsttimeflag would become illegal.
no subject
if (condition) LOOP_OVER_ALL_ELEPHANTS(elephant) { /* ... */ }Admittedly you might reasonably feel that I should just avoid calling the macro in any circumstances like that, which would be a fair enough position, but I note that all the other expansions discussed here (including the evil switch one) do work in that context.But the other, more important, reason is that it has a declaration in it, and in C90 declarations can't be interleaved with code. (For annoying reasons, the code in which I was using this macro is required to compile cleanly in C90 as well as C99.) So if I put any other statement before calling LOOP_OVER_ALL_ELEPHANTS, the declaration of
specialfirsttimeflagwould become illegal.