How to specify the destructor function during the extension of MicroPython using C

[Mars-CN]

In the process of using C to extend MicroPython, the construction method can be specified through make_new, but if the object is being destroyed, what should the destructor (or deinit) be specified through?

Because during the process of constructing objects, malloc needs to be used to create some space, and when the object is destroyed, free release needs to be called

[jimmo]

@Mars-CN you need to use m_new_obj_with_finaliser to construct the struct instance (so that the GC knows to call your finaliser), and then add a __del__ entry to your locals dict (this is your destructor/deinit method).

Look at e.g. extmod/modsocket.c for an example.

[Mars-CN]

I have tried this method, but in fact, MicroPython did not call it__del__ Corresponding function

a = A()
a = A()

If written this way, it should be called during the instantiation of the second A object__del__ Method, but not called unless manually called a.del () can only be used

[jimmo]

The finaliser isn't called until the garbage collector runs.

[Mars-CN]

How can we release resources without any references?

[Josverl]

You could use a deinit() method, or define __enter__ __exit__ to use with a context manager

To explicitly, or implicitly, perform your first level cleanup.