On Tue, 16 Jul 2002, Nicholas Clark wrote:
> 5.8.0 does the full fun and games of integer or floating point comparison:
>
> perl5.8.0-64 -le '$a = ~0; $b = $a & ~1; printf "%x <=> %x\n", $a, $b; print $a <=>
>$b; {use integer; print $a <=> $b}'
> ffffffffffffffff <=> fffffffffffffffe
> 1
> 1
>
> IIRC the speed difference was hard to benchmark. However, the ability to
> deal with large file offsets, windows device numbers and other 64 bit
> quantities correctly was seen as useful.
Let's not lose sight of the forest for the trees here -- the comparisons
are now *backwards*, which is considerably worse than imprecise. Here's
what I think the multimethod dispatch version would look like, without the
automatic multimethod dispatch:
INTVAL cmp (PMC* value) {
if (value->vtable == &Parrot_base_vtables[enum_class_PerlString]) {
FLOATVAL fdiff = (FLOATVAL)self->cache.int_val
- value->vtable->get_number(INTERP, value);
if (fdiff == 0) {
INTVAL idiff = SELF->cache.int_val
- value->vtable->get_integer(INTERP, value);
return idiff > 0 ? 1 : diff < 0 ? -1 : 0;
} else {
return fdiff > 0 ? 1 : -1;
}
}
else if (value->vtable == &Parrot_base_vtables[enum_class_PerlNum]) {
FLOATVAL diff;
diff = (FLOATVAL)SELF->cache.int_val
- value->vtable->get_number(INTERP, value);
return diff > 0 ? 1 : diff < 0 ? -1 : 0;
}
else {
/* int or indef */
INTVAL diff = SELF->cache.int_val
- value->vtable->get_integer(INTERP, value);
return diff > 0 ? 1 : diff < 0 ? -1 : 0;
}
}
Why not drop something like this in for the moment, then take another look
when we have multimethods?
/s
