Fawzi Mohamed wrote:
On 27-ott-10, at 18:59, Jonathan M Davis wrote:
On Wednesday, October 27, 2010 07:33:58 Fawzi Mohamed wrote:
An issue I encountered in D1 with invariant is using delete: I have a
method that deletes the current object, and obviously then any
invariant would fail.
It would be nice to have a way to disable invariant in that case.
In D2, as delete is not allowed anymore (if I got it correctly) this
is not a problem.
Except that calling a function on a deleted object would not be
desirable, so
having the invariant fail at that point would be a _good_ thing. If
anything,
you'd want _all_ function calls on a deleted object to fail invariant
or no
invariant, because none of them should be happening in the first place.
clear() in D2 does (or at least did - I don't know what it's current
state is)
put an object in its default state prior to any constructor call which
would
likely violate any invariant, which, on the whole, is a good thing as
well.
However, there was discussion of making a cleared object have a nuked
vtbl which
would be even better, since then all function calls on it would fail
period.
- Jonathan M Davis
...except that clear (just like my dealloc methods) at their end will
call the invariant...
*that* is what I was talking about,
:)
Fawzi
What for? It doesn't now, and it shouldn't (and most probably will not)
when it's design is solid and it's properly implemented.
The purpose of clear() is:
1) call dtor (which implies checking invariant *only before*
destruction), if object has it.
2) put an object in an invalid (from the compiler/runtime point of view)
state: this has been discussed at length, and latest discussion ended
with what Jonathan M Davis already mentioned: nuking object's virtual
call table.
3) Leave object's memory alone so GC will later decide what to do with it
If I haven't missed something, this is pretty much it. It's not a
method, it's a function -> no invariant checks after call.
