Get function or class method name from inside decorator in Python

Question

I have a following decorator.

def allow_disable_in_tests(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        version = ??? # name of the func of method’s class name
        need_to_switch_off_in_tests = cache.get('switch_off_in_tests', version=version)

        if settings.IM_IN_TEST_MODE and need_to_switch_off_in_tests:
            return None

        value = func(*args, **kwargs)
        return value
    return wrapper

There are 2 types of objects this decorator might accept as a func:

Standalone function.
Method of the class(bound method, static method and class method all possible)

Question is how to get from inside decorator name of the :

function in case of func is standalone function.
method’s class name in case of func is method of the class

This will be used in version .

Decorator should be able to work with both types of objects.

Thanks

@kubatucka . version = func.__qualname__.split('.')[0] returns func name in case of fucntion and class name in case of method. Better then i expected, thanks a lot. Please post full answer - i will accept it — Aleksei Khatkevich
– Aleksei Khatkevich, Commented Jun 19, 2020 at 14:48

Dunes · Accepted Answer · 2020-06-19 14:44:13Z

You can use __qualname__ and __module__ to derive this information. __qualname__ will describe where the class is defined within a module according to the class or function it was defined in.

However, you are putting test logic in production code, which is a bit of a code smell. You'd be better off using the monkey patching features of your testing framework to patch these functions when running your test suite. For example, with pytest:

import pytest
from functools import wraps
from inspect import signature

class FuncPatch:
    def __init__(self, parent, name, retval=None):
        self.parent = parent
        self.name = name
        self.retval = retval

def get_things_to_patch():
    import mymodule
    return (
        FuncPatch(mymodule, 'my_func'),
        FuncPatch(mymodule.MyClass, 'method'),
        FuncPatch(mymodule.MyClass, 'static'),
        FuncPatch(mymodule.MyClass, 'class_', retval='special'),
    )

def create_test_function(func, retval, decorator=None):
    func = getattr(func, '__func__', func) # unwrap if classmethod or normal method
    sig = signature(func)
    @wraps(func)
    def f(*args, **kwargs):
        # check func was called with correct params raises TypeError if wrong
        sig.bind(*args, **kwargs)
        return retval
    if decorator:
        f = decorator(f)
    return f

@pytest.fixture
def patch_all_the_things(monkeypatch):
    for patch in get_things_to_patch():
        decorator = None
        if (isinstance(patch.parent, type)
                and not callable(patch.parent.__dict__[patch.name])
        ):
            # quick hack to detect staticmethod or classmethod
            decorator = type(patch.parent.__dict__[patch.name])

        to_patch = getattr(patch.parent, patch.name)
        func = create_test_function(to_patch, patch.retval, decorator)
        monkeypatch.setattr(patch.parent, patch.name, func)

# things to test
def my_func():
    return 'my_func'

class MyClass:
    @staticmethod
    def static():
        return 'static'
    @classmethod
    def class_(cls):
        return 'class'
    def method(self):
        return 'method'

# actual tests
def test_my_func(patch_all_the_things):
    assert my_func() is None

def test_my_class(patch_all_the_things):
    assert MyClass().method() is None
    assert MyClass.method(MyClass()) is None
    assert MyClass.static() is None
    assert MyClass.class_() == 'special'

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