Or use #> ... <# which is shorthand for foreign-declare.
Another option is the feature-test egg, which is useful for complex cases,
and doesn't require that you redefine anything.
But for cases where it is safe to #define an undefined macro (in other words,
when you can guarantee there is an impossible, harmless or safe default value),
the above is easier.
On Aug 16, 2012, at 6:37 PM, Antony Lee wrote:
Hi all,
I am looking for a way to check if a symbol is #defined as a C macro or not... something like
(declare (foreign-declare "#include <foo.h>"))
(foreign-code #<<EOF
#ifndef FOO
#define FOO -1
#endif
EOF
)
(define-foreign-variable FOO int)
which doesn't work (because I cannot put C macros in foreign-code?).
My second try was to use the bind egg:
(bind* #<<EOF
#ifndef FOO
#define FOO -1
#endif
EOF
)
but now FOO is always redefined (i.e. #ifndef FOO always evaluates to true).
Any suggestions? (I guess I could always put all that in an actual header file full of #ifndef's and #include *that* one but I am looking for something more... elegant if possible.)
Thanks,
Antony