readonly member (but assignable at constructor time)

[lempiji]

On Friday, 27 April 2018 at 02:59:16 UTC, Dr.No wrote:
> In C# you can have a readonly member assignable either at 
> declaration or constructor time, like this:
>
> class C
> {
>   readonly myClass mc;
>
>   this()
>   {
>     mc = new myClass();
>   }
>
>
>   void doSomething()
>   {
>     mc = new myClass(); // wrong! result in compiler error, mc 
> is readonly
>   }
> }
>
> Does D have something like this natively or there's a way to do 
> so with traits/CTFE at runtime?

You can use std.experimenta.typecons.Final.
https://dlang.org/phobos/std_experimental_typecons.html#.Final