Peter Dimov wrote:
From: "Larry Evans" <[EMAIL PROTECTED]>
[snip]
This doesn't look correct to me... did you mean something like
struct X
{
Y * p;
explicit X(Y * p): p(p) {}
~X() { delete p; }
};
struct Y
{
shared_ptr<X> p;
};
int main()
{
Y * py = new Y;
shared_ptr<X> px(new X(py));
py->p = px;
px.reset();
}
?
Yes. I had thought about the need to delete the Y* in the
X::DTOR, but that was days ago and I forgot to include it.
I also thought a little more about it and what I was suggesting
was more like:
struc Y;
struct X
{
boost::unshared_cyclic_ptr<Y> y; //cyclic involves this arc.
explicit X(void): y(new Y) {}
};
struct Y
{
boost::shared_cyclic_ptr<X> x;
};
Where {unshared|shared}_cyclic_ptr use the detlef method to
record their offsets and hence enable tracing the pointer graph.
Then I'd imagine you'd ask, why not just use a shared_ptr<Y> instead
of bothering with unshared<Y>. The only answer I can think of is
that maybe that reflects better the meaning of the variable y.
The programmer knows it's never shared; so, he decides to
be explicit about it with unshared_ptr<Y>. If he had used
shared_ptr<Y>, then someone maintaining his code would have to wonder
who else is sharing this Y? Also, the overhead for unshared_ptr
would be at least a little less than shared_ptr (no reference count
or mark bit and no updating the reference count).
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