On Wednesday, 17 July 2013 at 11:28:18 UTC, Andrej Mitrovic wrote:
I often need to re-initialize a variable back to its
user-defined
initializer. For variables that have no user-defined
initializer, you
can simply use .init. For fields of structs or classes you can
actually use A.init.field, where A is the aggregate type. For
example:
-----
struct S
{
int value = 5;
}
void main()
{
S s;
s.value += 1;
s.value = S.init.value;
assert(s.value == 5); // ok
}
-----
But there's no equivalent for variables which do not belong to
any aggregate:
-----
void main()
{
int value = 5;
value += 1;
// value = ??
assert(value == 5);
}
-----
I think this is not a fair comparison. Your S s could be S s =
S(2) and you cannot retrieve S(2) just like in case with int
value = 5. I see no difference between basic type variables and
user-defined variables here.
Also, this reminds me replacing typedef by alias with loosing one
nice feature - you could do typedef MyInt int = 5; but not with
alias.
One workaround is to factor out the initializer to a manifest
constant, for example:
Other approach is to use UDA, it may be better then enum, but one
still need extra typing. Having new trait seems to be a good idea
but it needs to be figured out how it behaves in different
contexts.
