[RFA] Function return type checking
Daniel Jacobowitz
drow@mvista.com
Wed Feb 6 14:14:00 GMT 2002
On Wed, Feb 06, 2002 at 01:43:45PM -0800, Klee Dienes wrote:
> On Tuesday, February 5, 2002, at 08:07 AM, Daniel Jacobowitz wrote:
>
> >Have you considered casting the function itself? Something like:
> >(gdb) print ((float (*)(float)) fabs) (3.0)
> >$1 = 3.0
> >(gdb) set fabs
> >
> >Which, I will note, already works except for the fact that we neglect
> >the argument types on function pointers. Or
> >(gdb) set $fabs = (float (*)(float)) fabs
> >(gdb) p $fabs(4.0)
> >$2 = 4.0
>
> We have; for a long time that was the answer we gave to people who were
> running into this problem. Our experience was that it was a nightmare
> to explain to people how this mechanism worked, and that even for folks
> who did undertand it, they found it a major mental burden to use in
> practice. C function casting syntax is neither intuitive nor pleasant
> to type.
>
> The reason we chose the "cast" syntax wasn't so much to be cute, but
> because it was the first thing everyone tried when they were trying to
> get this to work. People would try 'print (float) fabs (3.0)', followed
> by 'print {float} fabs (3.0)', usually followed by several unsuccessful
> attemtps to remember the correct syntax to cast the function pointer.
>
> I also think there's a pretty solid rationale behind the syntax, and one
> that generalizes to argument-passing. The theory goes:
OK, I buy that. I'm still a little unhappy about the two possible
meanings of (int) fabs(3.0) - but it seems like a good compromise to
allow this syntax too. Thanks for the clarification.
--
Daniel Jacobowitz Carnegie Mellon University
MontaVista Software Debian GNU/Linux Developer
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