Re: dmd 1.046 and 2.031 releases - is() expression

[The Anh Tran]

Andrei Alexandrescu wrote:
I agree there are ugly constructs in D, and is-expressions would near 
the top of the list (particularly the absolutely awful is(T : T[])), but 
you have no case (heh) with the switch statement.


Andrei

Just a funny suggestion: could we change the is() expression to 
imperative style?

Now:
template Something(T, U, V) if ( is(T : T[]) && is(...) )
{
     alias T blah1;
     U blah2;
     class C {};
     struct S {};
}

In mirror universe:
template Something(T, U, V)
in
{
    static if ( T : T[] ) // static if here mean if (is (...))
    {
       // may do something with T, make alias, change type
       // or check another constraint.
    }
    else
    {
        pragma(msg, "T must be Klingon");
        static assert(false); // Or return false; ????
    }

    static if ( U == int )
    {
       V = float; // ?????
    }
    return true;
}
body
{
     alias T blah1;
     U blah2;
     class C {};
     struct S {};
}