Given a function object assigned to a name. How to get the name of the function as a string?
For example, consider the following function
your_function. How to get the name
"your_function" from this?
def your_function(): pass string_name = ???
Your desired value of the result stored in
string_name is the string
print(string_name) # your_function
Method 1: Use the __name__ Attribute
The most Pythonic way to extract the name from any object or class is to use its
__name__ attribute. Attributes enclosed in double underscores (dunder attributes) provide special functionality to Python programmers. For example, calling
your_function.__name__ yields the string value
def your_function(): pass string_name = your_function.__name__ print(string_name) # your_function
However, there’s an important case where this method will fail.
? ATTENTION: In Python, functions are objects. You can create multiple variables pointing to the same object in memory. Therefore, you could create two names
func_2 that both point to the same function object. When calling
func_1.__name__ the result may be
func_2 instead of
func_1 what you expected.
This is showcased in the following minimal example:
def func_2(): pass func_1 = func_2 print(func_1.__name__) # func_2
As both names point to the same memory object, but
func_2 was pointing to it first, the name of the object is
func_2. The memory usage of this code is visualized using the Python Tutor tool:
Both variables refer to the same function object that defaults as
Method 2: Use the __qualname__ attribute
To extract the name from any object or class, you can also use its
__qualname__ attribute. For example, calling
your_function.__qualname__ yields the string value
'your_function'. You’d use
__name__ if you’d also need some context such as the class defining the method.
The following code creates a function and a method inside a class. It then compares the output of the
__qualname__ attributes for both the function and the class:
def my_function(): pass class My_Class(object): def my_method(self): pass print(my_function.__name__) # "my_function" print(My_Class.my_method.__name__) # "my_method" print(my_function.__qualname__) # "my_function" print(My_Class.my_method.__qualname__) # "My_Class.my_method"
You can dive deeper into the idiosyncrasies of
__qualname__ here and here.
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