Re: [boost] shared_ptr Questions (& Bugs?)

From: Joe Gottman (joegottman_at_[hidden])
Date: 2001-03-18 21:50:55

----- Original Message -----
From: "Beman Dawes" <bdawes_at_[hidden]>
>  >1.  In share(), shouldn't the code "if (pn != rpn)" be "if (px !=
>  >rpx)"?
>
> They are equivalent.  Something is disastrously wrong if (pn != rpn) ==
(px
> != rpx).  Think about it.  If the two object pointers point to the same
> object, the two count pointer had better point to the same count.  I'll
add
> a comment to the code mentioning that.  Similar in shared_array.  I guess
> we could assert ((pn==rpn) == (px==rpx)), but it doesn't seem worth it to
> me.

px != rpx isn't quite equivalent to pn != rpn. Consider the following code:

shared_ptr<int> p1, p2; // p1 and p2 are both initialized with px == 0
p1 = p2; // px 's are equal, pn's are not. If share were to compare px's we
would have a memory leak in the pn's.

Joe Gottman