(This is a followup to yesterday's entry .)

Update : I'm actually completely wrong about this, both in practiceon x86 machines with gcc and, I believe, in standards-compliant theory,as brought to my attention by nothings in comments.

One general class of impossible-in-C varargs APIs is heavily polymorphicdispatch APIs where you need to dispatch to one of several differentvarargs functions that have different constant arguments. Here is agratuitous (and probably bad) API example:

I've noted before that dealing with varargs functionsin C is vaguely annoying (although not as annoying as in the days beforethe ANSI C stdarg support). One of those annoyances is that C's stdargsupport is limited compared to what you can do in languages with firstclass support for variable argument counts.

The core limitation in C is that you can't manipulate the list ofvariable arguments that your function gets. Instead you have twochoices; you can pass it completely unaltered to a function that