Andrej Mitrovic:
it just occurred to me that you can actually use a static
assert on a return type in D, e.g.:
import std.traits;
import std.algorithm;
auto min(T1, T2)(T1 t1, T2 t2)
{
return t1; // e.g. implementation bug
static assert(is(typeof(return) == CommonType!(T1, T2)));
}
void main() {
auto x = min(1, 1.0);
}
I didn't know this until now.
I'd like to verify the type of what a range yields inside the
post-condition of the function, but I can't use code like this,
because currently functions with out{} can't use auto as return
type:
import std.stdio, std.algorithm, std.traits;
auto foo(int x)
in {
assert(x >= 0);
} out(result) {
static assert(is(ForeachType!(typeof(result)) == int));
} body {
return map!(a => a * 2)([1, 2, 3]);
}
void main() {
writeln(foo(1));
}
And you have to keep in mind that inside the out{} 'result' is
const, and const ranges aren't that useful, you can't even
iterate them...
Bye,
bearophile
