I have a bp::wrapper wrapping an interface for use in python. Several
functions return reference types of other objects, for example:
class IFoo
{
virtual const IBar& getBar() const = 0;
}
I found that to get boost python to handle this scenario correctly and
eliminate any 'returning address of local variable' warnings I had to
trick the result converter like so:
class Foo_wrapper : IFoo, bp::wrapper< IFoo >
{
Bar _bar;
const IBar& getBar() const
{
_bar = *(IBar*)this->get_override( "getBar" )();
// return *(IBar*)this->get_override( "getBar" )(); <- works
as well but maybe less safe?
}
}
I was messing with this problem for the last day and a half and this
finally worked. From what I understand the method converter is
tricked into returning an IBar* by the cast, then I use the copy
constructor to make a concrete bar locally which is finally returned
as a reference to the calling code.
My first concern is if this is a 'proper' solution for this problem.
I found that by just doing
const IBar& getBar() const
{
return (IBar&)this->get_override( "getBar" )();
}
I would get crashes because the object returned from get_override
would be destroyed before I can copy it. IBar is abstract so most
'correct' uses will not work.
If this solution is acceptable my question is how is the result
converter dealing with the IBar* cast. Is it depending on me to
delete the pointer? Does this solution cause massive memory leaks?
Or will cleaning up the python object clean up the pointer as well? I
want to implement a 'proper' solution to minimize future potential
problems.
Thank you
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