On Mon, 13 Jul 2015 09:08:13 +0000, Yuxuan Shui wrote:

> No! What I want to do is to assign to 'const' only ONCE. So it is basically an initialization.

it is forbidden to do assigning to `const`. and D has *no* "uninitialized variable" thingy, even `x = void` is initialization too (in technical sense). so you want c++-like const, which `Rebindable` does.

> What I really want is to detach initialization from definition.

you can't. it's by design.

On 7/13/15 3:11 AM, Yuxuan Shui wrote:
> How can I do something like this?
>
> const(A) x;
> if (condition) {
>    x = func1();
> } else {
>    x = func2();
> }
>
> This is a valid use case, and to make this work I'll have to use
> Rebindable, which is really inconvenient.


auto xvalue() {
  if(condition) {
     return func1();
  } else {
     return func2();
  }
}
const(A) x = xvalue();

Essentially you can assign on initialization, so you have to encapsulate the initialization into one call. D allows nested functions quite easily, so you can do this.

You can also do a temporary lambda that you call immediately, but I'm not 100% sure of the syntax. Someone will chime in with the answer :)

-Steve

On Monday, 13 July 2015 at 14:41:36 UTC, Steven Schveighoffer wrote:
> You can also do a temporary lambda that you call immediately, but I'm not 100% sure of the syntax. Someone will chime in with the answer :)
>
> -Steve

Syntax is easy:

void main() {
    bool condition;
    const x = {
        if(condition) {
             return 1;
          } else {
             return 2;
          }
    }();
}

On Monday, 13 July 2015 at 17:18:53 UTC, Jesse Phillips wrote:
> On Monday, 13 July 2015 at 14:41:36 UTC, Steven Schveighoffer wrote:
>> You can also do a temporary lambda that you call immediately, but I'm not 100% sure of the syntax. Someone will chime in with the answer :)
>>
>> -Steve
>
> Syntax is easy:
>
> void main() {
>     bool condition;
>     const x = {
>         if(condition) {
>              return 1;
>           } else {
>              return 2;
>           }
>     }();
> }

This is pretty neat. Thanks!