On Wed, 11 Nov 2009 07:45:26 +0100, BCS <n...@anon.com> wrote:
Hello Walter,
When I originally worked out ideas for D, there were many requests
from the C and C++ community for a 'strong' typedef, and so I put one
in D. I didn't think about it too much, just assumed that it was a
good idea.
Now I'm not so sure. Maybe it should be removed for D2.
Does anyone use typedef's?
What do you use them for?
Do you need them?
I'd use them more if they were stronger. particularly, I'd love it if
they could be used to add/overide stuff basic types:
typedef int TD
{
TD opAdd(TD that) { assert(this < that); return cast(int)this +
cast(int)that; }
...
}
or even better
typedef int TD(T)
{
TD!(T) opAdd(TD!(T) that) if (Pred!(T)) = default; // use the default
but restrict the operation
...
}
We can already do that in D2:
struct myInt {
int _payload;
alias _payload this;
myInt opAdd( myInt that ) {
assert( this._payload < that._payload );
return this._payload + that.payload;
}
}
And I would believe this is why removing typedef is now being discussed.
I like typedefs for when I need a separate type with no bells and
whistles, and so suggest that
typedef int foo;
be kept as it is, and
typedef int bar {
/* stuffs */
}
be sugar for
struct bar {
int _payload;
alias _payload this;
/* stuffs */
}
--
Simen
