What is __main__.py?

by

Often, a Python program is run by naming a .py file on the command line:

$ python my_program.py

You can also create a directory or zipfile full of code, and include a __main__.py. Then you can simply name the directory or zipfile on the command line, and it executes the __main__.py automatically:

$ python my_program_dir
$ python my_program.zip
# Or, if the program is accessible as a module
$ python -m my_program

You’ll have to decide for yourself whether your application could benefit from being executed like this.

Note that a __main__ module usually doesn’t come from a __main__.py file. It can, but it usually doesn’t. When you run a script like python my_program.py, the script will run as the __main__ module instead of the my_program module. This also happens for modules run as python -m my_module, or in several other ways.

If you saw the name __main__ in an error message, that doesn’t necessarily mean you should be looking for a __main__.py file.

More Related Contents:

  1. Get a variable from the URL in a Flask route
  2. Python append() vs. + operator on lists, why do these give different results?
  3. Python and ClearCase setview
  4. What exactly do “u” and “r” string prefixes do, and what are raw string literals?
  5. How to split a list into pairs in all possible ways
  6. How to take partial screenshot with Selenium WebDriver in python?
  7. How to convert a given ordinal number (from Excel) to a date
  8. Why in numpy `nan == nan` is False while nan in [nan] is True?
  9. How to import all submodules?
  10. How to convert column with list of values into rows in Pandas DataFrame
  11. Command executed with Paramiko does not produce any output
  12. Asyncio.gather vs asyncio.wait
  13. Why print in Python doesn’t pause when using sleep in a loop?
  14. Serializing Foreign Key objects in Django
  15. How to sort IP addresses stored in dictionary in Python?
  16. Is there a way to auto-adjust Excel column widths with pandas.ExcelWriter?
  17. How do I load a caffe model and convert to a numpy array?
  18. Use Selenium with Brave Browser pass service object written in python
  19. How do I use a C-style for loop in Python?
  20. Howto determine file owner on windows using python without pywin32
  21. Making HTTP HEAD request with urllib2 from Python 2
  22. How to plot ROC curve in Python
  23. What is different between makedirs and mkdir of os?
  24. How to make a copy of a 2D array in Python? [duplicate]
  25. Imshow subplots with the same colorbar
  26. Python summing up time
  27. Installing mod_wsgi on WAMP server running on Windows 7
  28. How to hide file paths when running Python scripts in VS Code?
  29. automatically position text box in plot
  30. How Postgresql COPY TO STDIN With CSV do on conflic do update?

Leave a Comment