On Friday, 12 October 2012 at 07:36:37 UTC, Jonathan M Davis
wrote:
On Friday, October 12, 2012 07:53:09 monarch_dodra wrote:
Yes, as answered, opAssign may do things to this, such as
dealocate a payload, reduce a ref counter, or who knows what.
A valid point, but it would be easy to explicitly call the
invariant at the
beginning of opAssign if wanted to ensure that the object's
state was valid at
the beginning of opAssign. You can't _not_ call the invariant
though if the
compiler already does. And there's another problem which your
suggest against
init suggestion wouldn't fix. It's initializing to void:
S s = void;
If you ever want to do that, you can't have an invariant, or
it'll blow up
when you try and assign to it. And since it certainly wouldn't
be the same as
the init property, checking against the init property wouldn't
help you any.
- Jonathan M Davis
Well, again, you'd need your s to be in a valid state to assign
to it, so I'd *hope* the invariant blew up in my face.
When you declare s void, you are supposed to memcpy .init over it
manually, or call emplace (which does the same thing + more).
And you CAN have an invariant:
//----
import std.conv;
import std.c.string;
struct S
{
invariant()
{
assert(0);
}
}
void main()
{
S s = void;
static auto foo = S.init;
memcpy(&s, &foo, S.sizeof);
//or
emplace(&s);
}
//----
TA-DA!!!
