On Friday, 12 August 2016 at 14:41:14 UTC, Shachar Shemesh wrote:
That table was not expensive to compute, and its constantness
wasn't crucial enough even for me to put a wrapper pointer and
only access it through it. Had that not been the case, and had
that table been more expensive to computer, I'd probably
compute at compile time with an external tool.
Shachar
And you are forgetting about composability. If I can compute a
table at compile-time this means I can go higher on the
abstraction ladder.
void interpFast(string expr)(float x)
{
// here a look-up computed at compile-time
static immutable table = makeTable!exp(0, 100, 0.1f);
int ipart = cast(int)x;
int fpart = x - ipart;
return linInterp(table[ipart], table[ipart+1], fpart);
}
void main()
{
// automatically tabulated
float x = interpFast!"pow(cos(x) + 4, x)"(0.5f);
}
Not only is this impossible in C++, but being cumbersome it means
that people won't do it and loose optimization opportunities.
