Re: User defined implicit conversion

[Simon Wright <simon@pushface.org>]

Alain De Vos <devosalain71@gmail.com> writes:

> Casting from one type to another is a real pain.
> Does the functionality "User defined implicit conversion" exists?
> If not are there strategies, general rules, to limit conversion to a
> minimum ?
>
> We don't want as concatination :
> result := to_type_a (from_type_a (X) & from_type_a (Y)) ;
> when you could have :
> result := X & Y ;

   function "&" (L : Type_X, R : Type_Y) return Type_A;
   function "&" (L : Type_Y, R : Type_X) return Type_A;

which means that the tiresome manipulation only has to happen in one
place. Well, two places, unless you say

   function "&" (L : Type_Y, R : Type_X) return Type_A
   is (R & L);