On Friday, 4 April 2014 at 04:31:41 UTC, Walter Bright wrote:
On 4/3/2014 7:19 PM, bearophile wrote:
I have asked for fully typesafe enums in D,
You can do this:
struct MyInt {
int x;
alias this x;
... put your various constraints here ...
}
to get typesafe enums. In fact, you can use this construct to
create a type that overrides selected behaviors of any other
type.
Combined with your other post about casts, I'm not sure we're
talking about the same kind of type-safety. In the case of your
example, alias this does not make it typesafe, as a MyInt can
still be implicitly converted to int.
struct MyInt
{
int x;
alias x this;
}
void takesInt(int n)
{
}
void main()
{
//Fine
takesInt(MyInt(1));
}
Implicit conversions are generally not a facet of type-safe
systems. Saying that too-strong typing is bad because casts break
the type system is a strawman, although I agree that there is a
balance that must be struck.
