On 11/14/2011 09:54 PM, Per Knudsgaard wrote:
I have gotten (3) to work, but I am wondering about two things.
Since I couldn't get the constructor to work, I went for a modifier
that returns the object.
Sorry no one responded to your questions earlier. I havne't looked too
closely yet, but I thought I'd point out that you have basically written
a big workaround for the fact that you're using intrusive_ptr instead of
shared_ptr. Pretty much all of the things you're trying to do work
out-of-the-box with shared_ptr, and you don't have to worry about the
reference count yourself at all.
Unfortunately, similar support for intrusive_ptr isn't really present in
Boost.Python, but that's because intrusive_ptr isn't nearly as flexible.
So, two questions:
* Is this a legal/recommended way to do a modifier?
Legal, yes. I think. If switching to shared_ptr is a possibility, I'd
consider that the recommended way to deal with the entire problem.
Without it, I think you're in rather uncharted territory.
* If I only do a single INCREF, then the object is destroyed
while executing the NewObject().share() call. Why do I need two
INCREFs?
I'm a bit stumped by this, too, but I haven't looked as closely as I
might have if you didn't seem to have a satisfactory solution or if I
didn't think shared_ptr was really the way to go here. Part of the
explanation might be the fact that Boost.Python doesn't hold a reference
to what you get out of get_owner(), so you don't have one either, and
that might do funny things when the only Python reference is a temporary
object you're calling the share() method on. But I still would have
expected that to be safe.
HTH
Jim
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