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pythonscopeclosureslocal

Accessing variables in the local scope of a python decorator

Consider:

def g(value):
    def f():
        return value
    return f

x = g(3)
x() # prints 3

Given x in the example, the returned closure from g(3), is there any way to inspect that is the value of value without calling x()?

Solution

  • Yes, you can directly introspect the closure for a function in Python:

    >>> def g(value):
...     def f():
...         return value
...     return f
...
>>> func = g(42)
>>> func.__closure__
(<cell at 0x1077b5a80: int object at 0x1075b4618>,)

    Then if you want the value:

    >>> cell =  func.__closure__[0]
>>> cell.cell_contents
42