Lutger:
> We don't need an extension for this! Look:
>
> template Eval(string exp)
> {
> enum Eval = mixin(exp);
> }
>
> template IsConstant(string exp)
> {
> enum IsConstant = __traits(compiles, Eval!exp);
> }
>From what I see I think your code is useless for my purposes:
// D2 code
import std.stdio: writeln;
template Eval(string exp) {
enum Eval = mixin(exp);
}
template IsConstant(string exp) {
enum IsConstant = __traits(compiles, Eval!exp);
}
template Tuple(T...) { alias T Tuple; }
template Range(int stop) {
static if (stop <= 0)
alias Tuple!() Range;
else
alias Tuple!(Range!(stop-1), stop-1) Range;
}
long ipow(long x, int n) {
long result = 1;
static if (IsConstant!("n")) {
pragma(msg, "constant");
static if (n < 5) {
foreach (i; Range!(n))
result *= x;
} else {
for (int i; i < n; i++)
result *= x;
}
} else {
pragma(msg, "not constant");
for (int i; i < n; i++)
result *= x;
}
return result;
}
enum int w = 5;
void main() {
int x = 2;
const int y = 3;
enum int z = 4;
writeln(IsConstant!("x"), " ", IsConstant!("y"),
" ", IsConstant!("z"), " ", IsConstant!("w"));
// prints: false false false true
ipow(10, x);
ipow(10, y);
ipow(10, z);
}
Even "z" is seen as not constant?
Bye,
bearophile
