[C++-sig] Re: (no subject)

[Andrew Ellem]

> Andrew,
> 
> Clearly the error must be coming from somewhere else, for example
> a destructor of one of your objects which uses a HANDLE.  None of the
> Boost.Python code manipulates any type called HANDLE.
> 

You are correct in that it is my code that is causing the problem.  More

specifically, it is that Boost.Python is deleting one of my objects when
I 
don't want it to.

My problem is this:
In my class's constructor, I create a class that is implemented in
Python.  
The constructor takes a pointer to the calling class.
Some pseudo-code for clarity's sake:

class X {
   X() {
      Y y = PythonClass( this )
   }
}

The problem is that after the __init__ method is called, Boost tries to 
clean up the arguments, which causes my calling class to be deleted,
hence 
the crash.  So my problem is how do I prevent this?  

I'm guessing the problem is that by default Python passes by value, and
so
does Boost.  How do I do otherwise?  I'm guessing call-policies, but in
all
honesty I'm having some trouble getting my head around them all.

> Yes, it seems like you're taking shots in the dark.  Have you tried
> reading the documentation on Call Policies and/or stepping through the
> code that's crashing with a debugger?
 
I've read the documentation, but I admit I don't understand it 100%.
From
what I've read, I need to use a precall policy that tells Boost not to 
manage the variable I'm passing.  But I'm really not sure which policy
does
this, or even one exists.

I've been trying to find an example, the closest I can find is from the 
init.html example, which uses with_custodian_and_ward.  Is this what I
want
to do?  I don't really want to just throw it in and see if it works.

Perhaps a better question, where can I find a thorough explanation of
the
way Python, and Boost.Python handle arguments?  

Thanks for your help,

Andrew Ellem