How to create new closure cell objects?

Question

I need to monkey-patch my library to replace an instance of a symbol, and it\'s getting referenced by some function closures. I need to copy those functions (since I also ne

Answer 1

The simple way to make a closure cell would be to make a closure:

def make_cell(val=None):
    x = val
    def closure():
        return x
    return closure.__closure__[0]

If you want to reassign an existing cell's contents, you'll need to make a C API call:

import ctypes
PyCell_Set = ctypes.pythonapi.PyCell_Set

# ctypes.pythonapi functions need to have argtypes and restype set manually
PyCell_Set.argtypes = (ctypes.py_object, ctypes.py_object)

# restype actually defaults to c_int here, but we might as well be explicit
PyCell_Set.restype = ctypes.c_int

PyCell_Set(cell, new_value)

CPython only, of course.