preprocessing issues

[gaetanoortisi]

Hello,
I would like to know if there is some preprocessing trick available on
gcc that could expand something like:

debug(a)
debug(x,y, z)

as:

debug_a();

debug_x();
debug_y();
debug_z();

to help me debug many vars of different type.
Thanks,
Gaetano

 

[Jean-MArc Lienher]

Hello,
I would like to know if there is some preprocessing trick available on
gcc that could expand something like:

debug(a)
debug(x,y, z)

as:

debug_a();

debug_x();
debug_y();
debug_z();

to help me debug many vars of different type.
Thanks,
Gaetano

You can't have a variable number of parameters (except when using "...")
in a macro.

So :
#define debug1(p1) debug_##p1##();
#define debug2(p1, p2) debug_##p1##(); debug_##p2##();
#define debug3(p1, p2, p3) debug_##p1##(); debug_##p2##(); debug_##p3##();

This is the only solution in C99, but maybe there is some GNU extensions
that I don't know.

 

[Laurent Deniau]

Hello,
I would like to know if there is some preprocessing trick available on
gcc that could expand something like:

debug(a)
debug(x,y, z)

as:

debug_a();

debug_x();
debug_y();
debug_z();

to help me debug many vars of different type.
Thanks,

C99 allows to write such macro, no needs for gcc tricks.

Using the COS macros from:

http://cos.cvs.sourceforge.net/cos/COS/src/cos/fpp/

you can define the macro debug as (tested):

#define debug(...) FPP_SEP(FPP_MAP((__VA_ARGS__),debug_))
#define debug_(a) FPP_CAT(debug_,a)();

where FPP_SEP, FPP_MAP and FPP_CAT are macros available from fpp/
list.h

debug(a) -> debug_a();
debug(x,y,z) -> debug_x(); debug_y(); debug_z();

Other preprocessor libraries like Chaos can also be used instead of
COS fpp.

a+, ld.

 

[Jean-Marc Lienher]

C99 allows to write such macro, no needs for gcc tricks.

Using the COS macros from:

http://cos.cvs.sourceforge.net/cos/COS/src/cos/fpp/

Thank you for the information!!!

For my own education, I've tried to understand your macros.

Here is what I've understood :

#define count_args(...) get_nb_args(__VA_ARGS__, 3, 2, 1)
#define get_nb_args(pad1, pad2, pad3, n, ...) n

#define debug(...) debug_(count_args(__VA_ARGS__), __VA_ARGS__)

#define debug_(a, ...) debug##a(__VA_ARGS__)

#define debug1(a) debug_##a()
#define debug2(a, b) debug1(a); debug_##b()
#define debug3(a, b, c) debug2(a, b); debug_##c()

I've removed all the generic code to make it shorter and to work only in
this specific case.
It seems to work, but I've not carefully tested it in all situations.

 

[gaetanoortisi]

Thanks