@rmadsen-ks you can look at callbacktest.cs and test_callback.py for testing this.

@rmadsen-ks do you agree to transition from Zope to MIT license?

@denfromufa, Test passed. I have added a test verifying that the fix does what it should.

I agree to transition to MIT license.

how about garbage collection, is CLR or Python responsible? If Python, then I do not see Decref, so it would leak memory?

I have tested callbacks rapidly and the ref count does not increase permanently. Neither does it seem to leak when many new objects are made. I have tried creating 50M objects with no noticable leak.

I should not need to Decref for the following reason:

As the comment in pyobject.cs says, the PyObject assumes ownership. So if we want to convert a python object to a PyObject using ToManagedValue, we must increase the refcount when we are giving it to the constructor of PyObject. So I implemented that part. The PyObject decreases the ref count when the garbage collector cleans it up, which happens eventually. So when a new C# PyObject has been created from a python object, it will eventually be cleaned up by the .NET GC. Is some cases using(){} can also be used to give more predictable memory performance.

In the same way, if we want to convert C# PyObject to a python object, we increase the ref count, because now Python has an extra reference to it, so it needs ownership. Python will clean that up on its own when it goes out of scope.

@tonyroberts @vmuriart @filmor please review!

@rmadsen-ks this pull request does NOT resolve the issue described in #94:

dta@dta-Inspiron-N5050 ~/Downloads $ sudo pip install pythonnet-fix-develop-296-convert-PyObject.zip -U --force
Processing ./pythonnet-fix-develop-296-convert-PyObject.zip
Installing collected packages: pythonnet
  Found existing installation: pythonnet 2.2.0
    Uninstalling pythonnet-2.2.0:
      Successfully uninstalled pythonnet-2.2.0
  Running setup.py install for pythonnet ... done
Successfully installed pythonnet-2.2.0
You are using pip version 8.1.1, however version 9.0.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
dta@dta-Inspiron-N5050 ~/Downloads $ python
Python 2.7.6 (default, Jun 22 2015, 17:58:13) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import clr
>>> from System import Object, Array
>>> import sys
>>> a = Array[Object]([sys]) ; print a[0]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: value cannot be converted to Object

Hi, I'm not suggesting that it does. You want #94 fixed as part of this?

@denfromufa, is there anything I need to do to move this further or do I need to find another solution?

@rmadsen-ks your pull request is completely valid.

To me this also looks fine, but why do you introduce a new RefCount property? Either remove it or add tests for it, after that we can merge.

@filmor, I found it useful for verifying that I was not leaking reference counts. Without it, it is hard to get out the reference cound from C# as the NativeMethods are internal. It is not critical for me, so we can remove it.

@rmadsen-ks can you please open a new PR? I made a mistake and merged this pull request without seeing @filmor concern.

It is here #306