If name is main

Why?

Many times we read through python source code and found that there were some weird statments. And I always choose to ignore this statements until I found them everywhere and just want to figure it out.

if __name__ == '__main__':
  main()

To understand

In short, there is an classic explanation which summarize it well.

Make a script both importable and executable.

To understand this, there are two ways to run a python script. One is to run directly as a script. The other is to run as an imported module, and run from other python script.

Every python module has a variable __name__, when we run python script directly, __name__ is equal to __main__, hence, it will then run main(). However, if we run as an imported module __name__ will not equal to __main__. Therefore it won’t be run.