On 03/05/07, John Love-Jensen <eljay@xxxxxxxxx> wrote:
Hi Phil,
You can avoid it by using specialization.
For a 32-bit int, that would be 32 positive, and 32 negative
specializations.
Maybe a bit much, but it'd work.
HTH,
--Eljay
I think something like this should work, without needing so many
specializations:
template <int a, bool n = a<0>
struct rshift_by;
template <int a>
struct rshift_by<a, true> {
static int shift(int b) { return b << -a; }
}
template <int a>
struct rshift_by<a, false> {
static int shift(int b) { return b >> a; }
}
template <int a>
int shift (int b)
{
return rshift_by<a>::shift(b);
}
int f()
{
return shift<1>(1);
return shift<-1>(1);
}
It also avoids the if branch on the compile-time constant, though GCC
is quite good at optimizing those. (IIRC some other compilers (MSVC)
whine about it, though.)
~ Scott McMurray
P.S. I love how the template syntax gives a<0>, don't you?
