• Ben Jones (17/17) Nov 07 2020 I'm trying to write a function template with 1 parameter whose
• starcanopy (12/29) Nov 07 2020 template f(Ts...) {
• Ben Jones (2/6) Nov 07 2020 Ah, I had discovered a different error when I tried that. Thanks!

Ben Jones <fake fake.fake> writes:

I'm trying to write a function template with 1 parameter whose 
type is inferred, but with the other parameters variadic.

Basically, I want to do this:

auto f(Ts..., Inferred)(Inferred inf){}

and call it with f!(X,Y,Z)(w) //inferred will be typeof(w), Ts... 
== (X, Y, Z)

which I can't do because the variadic template args have to come 
last.

Is there a way to change f so that the caller can use it like I 
want?  I tried this approach which didn't work.

template f(Ts...){
   auto f(Inferred)(Inferred inf){}
}

I don't see a way to specify a variadic set of template args but 
have one inferred.  I could wrap the variadic args in another 
template so f just takes 2 params, but I'd like to avoid that 
because it makes the calling code more complicated.

starcanopy <starcanopy protonmail.com> writes:

On Saturday, 7 November 2020 at 20:43:04 UTC, Ben Jones wrote:
 I'm trying to write a function template with 1 parameter whose 
 type is inferred, but with the other parameters variadic.

 Basically, I want to do this:

 auto f(Ts..., Inferred)(Inferred inf){}

 and call it with f!(X,Y,Z)(w) //inferred will be typeof(w), 
 Ts... == (X, Y, Z)

 which I can't do because the variadic template args have to 
 come last.

 Is there a way to change f so that the caller can use it like I 
 want?  I tried this approach which didn't work.

 template f(Ts...){
   auto f(Inferred)(Inferred inf){}
 }

 I don't see a way to specify a variadic set of template args 
 but have one inferred.  I could wrap the variadic args in 
 another template so f just takes 2 params, but I'd like to 
 avoid that because it makes the calling code more complicated.

template f(Ts...) {
     auto f(Inferred)(Inferred inf) {
         pragma(msg, Ts);
         import std.stdio : writeln;
         inf.writeln;
     }
}

void main() {
     f!(int, float, char)("Hello, world!");
}

https://run.dlang.io/is/e8FGrF

Ben Jones <fake fake.fake> writes:

On Saturday, 7 November 2020 at 21:04:19 UTC, starcanopy wrote:
 void main() {
     f!(int, float, char)("Hello, world!");
 }

 https://run.dlang.io/is/e8FGrF

Ah, I had discovered a different error when I tried that.  Thanks!