__name__ in Python

As we know that Python does not have a main() function like C and C++. When the interpreter runs the program, code at level 0 indentation(very first line) starts executing. Before executing the code, the interpreter defines a special variable i.e. __name__.

If you are not familiar with __name__ don’t worry this post is for you. Follow the tutorial to understand the role of __name__ in Python.

Also read: Packing and unpacking arguments in Python

Note: __name__ variable is not available in the Python version below 3.x. 

__name__ in Python

In  Python, __name__ contains the name of the current module. If the same module is executing then the __name__ variable contains the “__main__” otherwise it contains the name of the module imported.

Suppose we have a Python program file name “codespeedy.py”. When we run the file “codespeedy.py” the value of __name__  will be  “__main__”. Another file with “tech.py”  is made and if we import “codespeedy.py” in “tech.py” the value of __name__ will be module name i.e. “codespeedy”.

For better understanding, let’s see an example. As described above create the first file with the name codespeedy.py.

def display(name):
    print(name)

print("__name__ value=", __name__)
print("Displaying Name:")
if __name__ == '__main__':
    display("Vimal Pandey")

Output:

__name__ value= __main__
Displaying Name:
Vimal Pandey

Now create the second file tech.py  and import the first file codespeedy.py in it.

import codespeedy
codespeedy.display("Python Programming")

Output:

__name__ value= codespeedy
Displaying Name:
Python Programming

When the tech.py is executed then the value of __name__  changed to codespeedy from __main__.
That’s why  if__ name__ ==”__main__”  is used to prevent the ceratin lines of code from being imported into another program.

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