Am 10.08.23 um 03:00 schrieb Junio C Hamano:

Jeff King [off-list ref] writes:

quoted

  int my_foo;
  ...
  OPT_CALLBACK('f', "foo", int, &my_foo, ...etc);

Not great, but it might not be _too_ bad given that most helpers like
OPT_BOOL() can just say "int" behind the scenes.

That said, I don't recall these void pointers being a large source of
errors in the past. So while it's a fun type-system puzzle, the
effort/reward ratio might not be favorable.

I have vague memories of changing a callback from using a string_list
to a strset (or whatever) and getting crashes out of some other callers
that used it non-obviously via some macro.  A compile-time check would
have helped me.

I tend to agree on both counts, it is a fun puzzle, and it probably
is not going to give us sufficient reward.  The fact that "int" and
typeof(my_foo) need to be manually kept straight defeats the "type
safety" justification for this mental exercise.

The many-pointers idea is a bit silly, admittedly.

Having to declare a type manually is how most of C's type safety works,
though, so a certain amount of that is unavoidable.

typeof (along with typeof_unqual) is nice, but I guess it will take a
few years (or decades?) before we can expect it to be supported by all
relevant platforms.

The typed-callback-with-void-wrapper idea seems promising.  Let's see
if we can get it into usable shape.

René