I can't figure out if there is a way to run a specialized cleanup function when a module needs to be "unloaded" (i.e. just before a reload() or when i quit the interpreter).
I'm thinking of something like tp_dealloc.
If I call Py_InitModule3 and look at module->ob_type->tp_dealloc, I find that Python provides a default tp_dealloc for me.
Now, suppose my module needs to allocate some resources at startup, I'm not sure, but I think I'd have to do it in my PyMODINIT_FUNC, right?
But, if I reload() my module or if I quit the Python interpreter, I'd like to free those resources (before allocate them again, in case of a reload).
En Fri, 29 Jan 2010 19:50:52 -0300, Mr.M <m...@unknown.nospam> escribi :
> I can't figure out if there is a way to run a specialized cleanup > function when a module needs to be "unloaded" (i.e. just before a > reload() or when i quit the interpreter).
I think what you want to do isn't possible with Python 2, and it's one of the reasons the module handling was redesigned in Python 3.x; see PEP 3121.
> I'm thinking of something like tp_dealloc.
m_free (PyModuleDef member, in Python 3) might work for this.
> I think what you want to do isn't possible with Python 2, and it's one > of the reasons the module handling was redesigned in Python 3.x; see PEP > 3121.
Thank you Gabriel for your help. Unlucky I can't use Python 3.x in my project, sob!
> I can't figure out if there is a way to run a specialized cleanup > function when a module needs to be "unloaded" (i.e. just before a > reload() or when i quit the interpreter).
> I'm thinking of something like tp_dealloc.
> If I call Py_InitModule3 and look at module->ob_type->tp_dealloc, I find > that Python provides a default tp_dealloc for me.
> Now, suppose my module needs to allocate some resources at startup, I'm > not sure, but I think I'd have to do it in my PyMODINIT_FUNC, right?
> But, if I reload() my module or if I quit the Python interpreter, I'd > like to free those resources (before allocate them again, in case of a > reload).
> Is there a way to make this work?
Gabriel already pointed you to the module cleanup support in Py3, which can be used to provide reload capabilities to your module.
In Py2, there are at least some ways to free resources when terminating the interpreter. See the "atexit" module and the Py_AtExit() function:
Note that both have their specific limitations, though, as you can see from the docs.
Also note that it might help you to take a look at Cython, a Python-to-C compiler for writing fast C extensions. It has an option for generating module-level cleanup code automatically, and generally simplifies writing binary extension modules quite a bit.
> Note that both have their specific limitations, though, as you can see from > the docs.
> Also note that it might help you to take a look at Cython, a Python-to-C > compiler for writing fast C extensions. It has an option for generating > module-level cleanup code automatically, and generally simplifies writing > binary extension modules quite a bit.
> Stefan
Thank you very much Stefan for your reply, I'll study the sources you have pointed me to.
Could I allocate my resources in a "static" object (without publishing the type of that object so that I can't instantiate another one) linked to my module? This way, when I stop the interpreter, the object will be destroyed calling its destructor.
> Could I allocate my resources in a "static" object linked to my module?
Sure, but you will have to let CPython know about it so that it can see that the reference is only held by the module that it is cleaning up. Otherwise it can't collect the reference. This works easily in Py3 but not in Py2.
at the module level and let Cython generate the cleanup code for it. In C, you have to implement an atexit function and decref the resource object either there or in the module cleanup function of Py3.
> (without publishing > the type of that object so that I can't instantiate another one)
Note that there is the type() builtin function which returns the type given an instance. So you can't hide the type.
