tuples are definitely a compile-time job. You could do something
like this to build an N tuple by calling a function N many times.
---
import std.typecons;
int foo() {
return 3;
}
auto initTuple(size_t N, alias func)() {
string magic() {
string result = "return tuple(";
foreach(i; 0..N) {
result ~= "func(),";
}
result ~= ");";
return result;
}
mixin(magic());
}
void main(string[] argv) {
enum Tuple!(int, int, int) tup = initTuple!(3, foo);
}
---
This just builds the tuple by building up a mixin string which
calls the function so many times, with no guarantees about the
order of arguments. If you have side-effects in your function
though, you probably want to move it runtime anyway and use a
range with the 'repeat' function, etc.
