initialization immutable array

[Yota via Digitalmars-d]

On Thursday, 15 May 2014 at 16:13:59 UTC, AntonSotov wrote:
> DMD 2.065
> I do not know much English. sorry.
>
> need to initialize immutable array  "_items"
> //-------------------------------------------------------
> module main;
> import std.stdio;
>
> class Zond {
>   this() {
>     foreach (i; 1..4) {
>       _items ~= i;  // is expected ERROR
>     }
>   }
>
>   immutable(int[]) _items;
> }

You're only allowed to assign an immutable value in a constructor 
once, which is why it doesn't let you do so in a loop.  As for 
the second example, that looks like a bug to me.

Here are a couple ways to initialize the array:

1:
   this() {
     import std.exception : assumeUnique;
     int[] items;
     foreach (i; 1..4) {
       items ~= i;
     }
     _items = items.assumeUnique;
   }

2:
   this() {
     // The result of a pure function may be implicitly cast to 
immutable.
     _items = function() pure {
       int[] items;
       foreach (i; 1..4) {
         items ~= i;
       }
       return items;
     }();
   }

BTW, this would be better suited to the digitalmars.D.learn group.