On Friday, 20 November 2020 at 14:08:23 UTC, jmh530 wrote:
Doing something like below fails because I don't seem to be
able to make a templated lambda that just takes types. Is the
only way to do something similar to create a separate function
to handle the condition, or is there some other way to do
something with similar flexibility?
import std.stdio: writeln;
import std.meta: allSatisfy;
void foo(Args...)(Args args)
if (allSatisfy!(x => is(x == double), Args))
{
writeln("works");
}
void main() {
foo(1.0, 2.0);
}
There is no way to create an anonymous template in D. You will
have to declare a separate helper template:
private enum isDouble(T) = is(T == double);
void foo(Args...)(Args args)
if (allSatisfy!(isDouble, Args))
{
// ...
}
In this specific case, you could also make `foo` a type-safe
variadic function [1], which would eliminate the need for
`allSatisfy`:
void foo(double[] args...)
{
// ...
}
[1]
https://dlang.org/spec/function.html#typesafe_variadic_functions
