On Mon, 08 Aug 2011 15:47:36 -0400, Christian Manning
<[email protected]> wrote:
Philippe Sigaud wrote:
Hi Chris,
import std.typecons;
void main() {
auto x = 1;
Tuple!(int,short) a;
a[0] = 1;
a[x] = 2;
}
If I use a value instead of a variable ie. a[1] = 2; it compiles fine.
The index need to be a compile-time constant, you cannot index a tuple
with a runtime value.
Try using
enum x = 1;
Philippe
Ah I didn't know this, thanks. That makes a tuple pretty useless for
what I
was doing now as I was reading the "index" in from a file. Guess I'll
find
another way round it.
You still can do it, but you have to do it by still using compile-time
constants as indexes:
auto x = 1;
Tuple!(int, short) a;
a[0] = 1;
switch(x)
{
case 0:
a[0] = 2;
break;
case 1:
a[1] = 2;
break;
default:
assert(0, "does not compute!");
}
the point is, the compiler has no idea what the lvalue expression's type
should be when you do:
a[x] = 1;
is it short or int?
so the compiler must *know* what type x is at compile time in order for
this to be valid.
-Steve
