clear bug?

[Jonathan M Davis]

On Tuesday, September 06, 2011 02:12:11 Andrej Mitrovic wrote:
> On 9/6/11, Jonathan M Davis <jmdavisProg at gmx.com> wrote:
> > Why would you
> > ever try and use an object that had been cleared?
> 
> TDPL, that's why. Things might have changed but how would someone new
> to D know that?

I really don't pay much attention to clear, since I rarely use it, and I don't 
know why you'd ever actually want to try and use an object that you cleared. I 
do remember discussions about making it clear out the vtable, since you _want_ 
it to blow up after it's been cleared rather than have an invalid object work 
on some level. Rereading the relevant section in TDPL though, it does look 
like it describes a different situation than seems to have been ultimately 
settled on. So, I guess that I don't know exactly what the situation currently 
is or what it's supposed to be. But I wouldn't have expected clear to result 
in a valid object. But clearing out the vtable at least makes it blow up 
nicely instead of doing who knows what with memory when you try and call 
functions on an invalid object. So, if the ultimate goal is just to make it 
memory safe, then both clearing out the vtable and the situation that TDPL 
describes do the trick, though deleting the vtable actually helps tell you 
that you've used an object when you shouldn't, whereas TDPL's description 
results in using the object succeeding, which probably isn't a good thing.

- Jonathan M Davis