On Friday, 30 August 2013 at 15:41:55 UTC, Namespace wrote:
I believe typedef was deprecated due to no-one being able to
agree on the semantics (although it's a bit before my time). I
think it needs to come back as a very simple concept:
A type duplication. e.g. typedef int myInt; (or typedef myInt
= int;) creates a new type that is exactly identical to int,
but is a distinct type in the type system.
It should provide *exactly* identical behaviour to e.g. having
two structs with identical contents but different names. E.g.
struct A{}
typedef A tA;
alias A aA;
alias tA atA;
typedef aA taA;
assert(!is(tA == A));
assert(is(aA == A));
assert(is(atA == tA));
assert(!is(taA == atA));
etc....
It's a really basic feature that D ought to have.
I don't understand the difference to alias myInt = int;
Isn't it the same?
Typedef was useful not for poking around new type with same
properties - new name of existing type, but for non-trivial
default value:
typedef int myint = 1;
void main()
{
myint my;
assert(my is 1);
}
Alias does not provide this feature, so D hadn't become better
with this depreciation (actually the opposite). Nor it had with
delete operator depreciation for the replacement of destroy,
which like in case with typedef, does not cover full old feature
functionality (and functionality what destroy() does provide is
useless in many cases). I consider both depreciations as mistakes.
