An interesting and potentially useful feature of prototype
function signatures could be the ability to have parameters
after ellipses such as

void f(char *p ... char *q);

This would mean that the first parameter must be a char * and
the last parameter must be a char *, but there can be any
number of any type of parameter between.  A case where this
would be useful would be for NULL terminated lists of
parameters such as is found in the X Toolkit.


void XtVaSetValues(Widget w ... char *null_terminator);

This would force the final NULL to be interpreted as a char *,
instead of as an integer when you use

XtVaSetValues(w,{various resources and values},NULL);

It would also help avoid accidentally leaving off the
NULL.

The parameters after ellipses would work slightly differently
than normal parameters.  Since they would still have to be
interpreted with va_arg they would still have to go
through the untyped parameter conversions so that

void f(... char);

when called as

f(786);

would be interpreted as if f had been declared

void f(...);

and was called like

f((char)786);


What are your opinions?

  Until Later,
  Vaughn Cato (gcato@st6000.sct.edu)