054-flask/docs/wiki/Lecture-4-Name-and-Main.md

Lecture 4: name and main

English · Dansk · Bahasa Malaysia

What the lecture covers

__name__ is a built-in variable that holds the name of the current module. When a file is run directly Python sets it to "__main__"; when the file is imported it holds the module name. Checking if __name__ == "__main__": lets a file decide what runs only when it is the main program, for example app.run(). That gives a second way to start the Flask server, next to flask run, and it makes starting and stopping easy during development.

What we gained

• The rule that code runs correctly whether a file is run or imported.
• A main() function in hello.py that is only called under the __main__ check, so importing it never starts a server.
• A tested example (describe_name) that explains the two cases in words.

In this repository

Code: src/flask_day_54/presentation/hello.py (main) and src/flask_day_54/domain/name_demo.py. Tests: tests/unit/test_name_demo.py and tests/e2e/test_hello_main.py.