alright, here's another example why eval is a good idea:
#define A 17
#define B 153
#define N1 ((A + B)/2) /* intended was (17 + 153)/2 */
#undef A
#define A 230
#define N2 ((A + B)/2) /* intended was (230 + 153)/2 */
printf("%u %u", N1, N2);
sure, you can assign N1 to a static const, say N1_var, then invoke that in when
printf is finally called. or simply print N1, then after the undef print N2.
but what if we have to use both N1 and N2 in the same conditional expression??
everybody should be aware by now that there's a lot of ugly dependencies in cpp.
but for a *fairly complex*(1) conditional directives, spanning several files,
you have to call the macros all at the same time and not one one-by-one. to get
around it (if possible) is to employ an even more complex system of defs and
conditionals... or you can use external scripts to generate the codes. but like
i said, these could just be small snippets of codes, where having scripts is
un-minimalistic.
eval takes away all the ugliness.
(1) by fairly complex, i mean one that doesn't really merit a script/macro
processors to be written.
alright, if i can't convince the developers, would a maintainer (or anybody
that knosw their way around libcpp) please help me out on how to get started my
port for the feature... i actually don't like the idea of writing a plugin.
