I want to have one of the parameters on a function be optional. The problem is, is that it's a AA and D does not seem to support empty AA literals. Observe:

string func(int a, int[int] b = []) {
    return "mem1";
}

void main() {
    func(1);
}

$ dmd test
test.d(8): Error: cannot implicitly convert expression ([]) of type void[] to int[int]

This doesn't work either

string func(int a, int[int] b = int[int].init) {
    return "mem1";
}

void main() {
    func(1);
}

On Thursday, 3 March 2016 at 22:06:54 UTC, Jack Stouffer wrote:
> I want to have one of the parameters on a function be optional. The problem is, is that it's a AA and D does not seem to support empty AA literals. Observe:
>
> string func(int a, int[int] b = []) {
>     return "mem1";
> }
>
> void main() {
>     func(1);
> }
>
> $ dmd test
> test.d(8): Error: cannot implicitly convert expression ([]) of type void[] to int[int]
>
> This doesn't work either
>
> string func(int a, int[int] b = int[int].init) {
>     return "mem1";
> }
>
> void main() {
>     func(1);
> }

Use null:

string func(int a, int[int] b = null) {
    return "mem1";
}

void main() {
    func(1);
}

On 03/03/2016 02:06 PM, Jack Stouffer wrote:

> This doesn't work either
>
> string func(int a, int[int] b = int[int].init) {

Parentheses around int[int] works though. I don't know whether it's a bug.

string func(int a, int[int] b = (int[int]).init) {

Ali