Is this a bug in the standard?
Norman Diamond
diamond at diamond.csl.sony.junet
Mon May 8 11:02:57 AEST 1989
In article <189 at riunite.ACA.MCC.COM> rfg at riunite.UUCP (Ron Guilmette) writes:
>Well, I hope that Subject: line caught your attention.
Well, I think it's a bug in the standard. And in C++, where you first
asked this question. At least this one is a reasonable bug, i.e. hard
to foresee.
>Is there any completely type-safe way to declare a function
>(using function-prototype style) which can accept a
>pointer to itself as a parameter?
Seems to me that ARK's answer in comp.lang.c++ is correct; it's impossible.
But if you're content to wrap it in a struct, you get type-safety:
union bar_t;
typedef int foo_t (union bar_t); /* gets a warning from gcc 1.32 */
typedef foo_t *foo_ptr_t;
typedef union bar_t {
foo_ptr_t foo_ptr;
} bar_t;
foo_t foo; /* your prototype is done, sir */
bar_t make_bar (foo_ptr_t a_foo_ptr)
{
bar_t my_bar;
my_bar.foo_ptr = a_foo_ptr;
return my_bar;
}
int foo (bar_t bar)
{
if (bar.foo_ptr == &foo)
{
printf ("Hello world, it's me!\n");
return 0;
} else {
printf ("Goodbye, cruel world!\n");
return 1;
}
}
main()
{
foo (make_bar (&foo));
}
--
Norman Diamond, Sony Computer Science Lab (diamond%csl.sony.co.jp at relay.cs.net)
The above opinions are my own. | Why are programmers criticized for
If they're also your opinions, | re-inventing the wheel, when car
you're infringing my copyright. | manufacturers are praised for it?
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