On Tuesday, 17 August 2021 at 20:29:51 UTC, james.p.leblanc wrote:
So, below
is my code:
import std.stdio;
import std.meta : AliasSeq;
template isAmong(T, S...) {
static if (S.length == 0)
enum isAmong = false;
else
enum isAmong = is(T == S) || isAmong(T, S[1..$]);
}
alias MyTypes = AliasSeq!(int, float);
auto myFunc(T)(T a, T b) if (isAmong!(T, MyTypes)) {
writeln(" in myFunc ");
return;
}
void main(){
writeln("started ...");
auto a = 1;
auto b = 2;
myFunc!(int)(a, b);
return;
}
And, here are the error message:
(master) Notes > dmd recursive_template.d
recursive_template.d(9): Error: circular reference to variable
`recursive_template.isAmong!(int, int, float).isAmong`
recursive_template.d(17): Error: template instance
`recursive_template.isAmong!(int, int, float)` error
instantiating
recursive_template.d(29): while looking for match for
`myFunc!int`
Can anyone see what is going on?
Best Regards,
James
https://run.dlang.io/is/m5svQ2
The error was in line 8.
T (Teoh) forgot to take the first of `S` in `is(T == S[0])`. The
error message improves after adding the `!` in `isAmong!(T,
S[1..$])`, which, surprisingly, is optional!
— Bastiaan.
