Re: Discussion Thread: DIP 1039--Static Arrays with Inferred Length--Community Review Round 1

[Luhrel via Digitalmars-d-announce]

On Wednesday, 6 January 2021 at 19:04:14 UTC, jmh530 wrote:
On Wednesday, 6 January 2021 at 18:34:31 UTC, Nick Treleaven 
wrote:
[...]

What about something like below to handle any user-defined type.

import std.stdio: writeln;

template staticArray(T) {
    T[n] staticArray(ulong n) (auto ref T[n] a) {return a;}

    T[n] staticArray(U, ulong n) (auto ref U[n] a)
        if (!is(T == U))
    {
        T[n] output;
        for(size_t i = 0; i < n; i++) {
            output[i] = cast(T) a[i];
        }
        return output;
    }
}

T[n] staticArray(T, ulong n) (auto ref T[n] a) {return a;}

struct Foo {
    float x;
    T opCast(T)() {
        return cast(T) x;
    }
}

void main(){
    auto a = [1,2,3].staticArray!float;
    pragma(msg, typeof(a)); // float[3]
    a.writeln();
    [1,2,3].staticArray.writeln();

    auto b = [1,2,3].staticArray!Foo;
    b.writeln();
}

This works fine, even in betterC mode with LDC.
Doesn't work with betterC with DMD 
(https://issues.dlang.org/show_bug.cgi?id=19946).

I still don't like the .staticArray, but I'll use it if this DIP 
isn't approved.

Maybe `[$]` can be a shortcut to .staticArray.