Swig / Python memory leak detected

Question

I have a very complicated class for which I'm attempting to make Python wrappers in SWIG. When I create an instance of the item in Python, however, I'm unable to initialize certain data members without receiving the message:

>>> myVar = myModule.myDataType()
swig/python detected a memory leak of type 'MyDataType *', no destructor found.

Does anyone know what I need to do to address this? Is there a flag I could be using to generate destructors?

Thanks for any help you can offer!

Answer 1

The error message is pretty clear to me, you need to define a destructor for this type.

Answer 2

For reasons specific to the project, our classes have no methods. They're effectively structs. Given that I am not permitted to add any function (including a destructor), do I have any options available to me?

I also find it strange that while -none- of my classes have a constructor or destructor, only some of them bug out with this "memory leak detected!" message. Why wouldn't it be consistent?

Answer 3

SWIG always generates destructor wrappers (unless %nodefaultdtor directive is used). However, in case where it doesn't know anything about a type, it will generate an opaque pointer wrapper, which will cause leaks (and the above message).

Please check that myDataType is a type that is known by SWIG. Re-run SWIG with debug messages turned on and check for any messages similar to

Nothing is known about Foo base type - Bar. Ignored

Receiving a message as above means that SWIG doesn't know your type hierarchy to the full extent and thus operates on limited information - which could cause it to not generate a dtor.

Answer 4

[Apologies for answering rather than commenting -- I just registered formally so it doesn't recognize me as the original poster and I don't have the reputation points.]

Thanks very much, ASk. I've been running Swig with the -Wall flag and it doesn't give me any warnings. I also tried using the debug flags for classes and typedefs and still didn't see anything that looked alarming.

Honestly, I could live with the memory leak -- I'm only concerned with it because I suspected that it might be the cause of another, more critical problem I was having.

Do you happen to have any other suggestions? Much obliged for all your assistance thus far!