More flexible array of array allocation syntax

[dlangBugzillaToGithub]

bearophile_hugs reported this on 2015-01-22T09:50:46Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=14026

CC List

• Temtaime

Description

Perhaps we can support this syntax:

void main() {
    uint n = 10; // Run-time value.
    int[][3] m = new int[][3](n);
}


That in dmd2.067alpha gives:

test5.d(3,30): Error: function expected before (), not new int[][](3u) of type int[][]


That means:

void main() {
    uint n = 10; // Run-time value.
    int[][3] m;
    foreach (ref a; m)
        a.length = n;
}

[dlangBugzillaToGithub]

temtaime commented on 2015-01-22T17:43:24Z

Why not int[][3] = new int[n][3]; ?
I think it's better.

[dlangBugzillaToGithub]

bearophile_hugs commented on 2015-01-22T17:51:27Z

(In reply to Temtaime from comment #1)
> Why not int[][3] = new int[n][3]; ?
> I think it's better.

That syntax is already taken. n needs to be a compile-time constant, and it creates something different:

void main() @safe {
    enum int n = 2;
    auto m = new int[n][3];
    pragma(msg, typeof(m));
}

Output:

int[2][]

[dlangBugzillaToGithub]

temtaime commented on 2015-01-22T19:07:41Z

It's too strange in fact because for one dimension it works:

int n;
auto arr = new int[n];