Python File Structure¶
REQ: Introduce the standard structure used in Python scripts and modules.
WHY: Consistent structure improves readability and reuse.
OBS: This structure is reused across projects.
Standard Python Programs¶
Professional Python programs typically follow this order:
- imports at the top
- clearly named variables
- a
main()function - a conditional execution guard
This structure appears in both small scripts and large codebases.
The main() Function¶
A main() function groups the primary actions of a script.
OBS:
The function name main is a convention.
It signals where execution begins when a file is run directly.
Conditional Execution Guard¶
Python files often end with this block:
if __name__ == "__main__":
main()
This pattern is standard across Python projects.
What the Guard Means¶
The variables with double underscores (often called dunders) are built into every Python module automatically.
This conditional block means:
- when the file is run directly,
main()is executed - when the file is imported,
main()is not executed
This allows the same file to function as both:
- a runnable script
- an importable module
Reuse¶
This structure is reused consistently.
Consistent structure:
- reduces cognitive load
- supports testing and reuse
- makes programs easier to understand and extend