Hi,
Dan McMahill <[EMAIL PROTECTED]> writes:
> I can do something like
>
> SCM scm_myfn(SCM flags)
> {
>
> myfn (scm_num2int (flags, SCM_ARG1, "myfn"));
>
> return SCM_BOOLEAN_T;
>
> }
>
> but I'm not sure of the best way to define the flags in scheme. Or
> maybe this is not "the scheme way".
What you describe above is doable and is an approach sometimes taken.
See for instance the POSIX functions in Guile, e.g., `popen'.
Personally, I prefer to pass a list of symbols rather than a single
number in such situations. This might require some more work if you
need to convert those flags to a C or'ed integer, but not so much
because (i) symbols can be compared with `eq' which is fast, (ii)
the list of flags may usually be small, and (iii) the number of values
that can be taken by the flags is small as well.
SCM_DEFINE (scm_func, "func", 0, 0, 1,
(SCM flags),
"My function takes any number of symbols.")
#define FUNC_NAME "func"
{
int c_flags;
for (c_flags = 0;
scm_is_pair (flags);
flags = SCM_CDR (flags))
{
SCM f = SCM_CAR (flags);
if (scm_is_eq (f, my_first_flag_sym))
c_flags |= MY_FIRST_FLAG;
else if (scm_is_eq (f, my_second_flag_sym))
c_flags |= MY_SECOND_FLAG;
else
scm_wrong_type_arg (FUNC_NAME, 1, f);
}
/* ... */
}
#undef FUNC_NAME
But this is debatable and it also depends on the context.
Thanks,
Ludovic.
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