Function and Method Objects

Everything is an object in Python, even functions and member functions.

def my_function():
    print('Oh, you called me!')
    
print(type(my_function))
print(id(my_function))
print(dir(my_function))

<class 'function'>
140438181160432
['__annotations__', '__builtins__', '__call__', '__class__', '__closure__', '__code__', '__defaults__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__get__', '__getattribute__', '__globals__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__kwdefaults__', '__le__', '__lt__', '__module__', '__name__', '__ne__', '__new__', '__qualname__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__']

print(my_function.__name__)

my_function

Member functions are bit special.

class my_class:
    def some_method(self, some_string):
        print('You called me with {}'.format(some_string))

my_object = my_class()

print(type(my_object.some_method))
print(type(my_class.some_method))

<class 'method'>
<class 'function'>

If the method my_object.some_method is called, then the Python interpreter inserts the owning object as first argument and calls the corresponding function my_class.some_method. In other words, the following two lines are equivalent:

my_object.some_method('Hello')
my_class.some_method(my_object, 'Hello')

You called me with Hello
You called me with Hello