ALL-MODU0002 · module_member_count

Measure top-level classes and functions as a deterministic focus proxy.

This is a deterministic rule for all languages. Read its implementation.

Definition

Count the synchronous functions, asynchronous functions, and classes one module declares directly at module scope, and return their sum. Imported names and nested declarations do not count, because the question is how many things this file asks a reader to hold at once rather than how many names it can reach.

The count is a navigation proxy and nothing more. Ten declarations do not mean ten ideas, which is why the measurement stops here and a project policy owns the ceiling, and why the contextual module-cohesion rule is the one that judges whether the responsibilities actually differ.

Evidence

The finding names the module and its class and function counts separately, so a file wide in one and narrow in the other is distinguishable. The value is the number of classes and functions the module declares at its own scope.

Exceptions

A cohesive schema family that outgrows a reasonable ceiling is better answered by becoming a package with one model per file and a narrow __init__.py export surface than by raising the ceiling. A public facade and a compact declarative registry are wide on purpose and are where a project raises it instead. wemake-python-styleguide WPS202 offers a stricter default of seven combined members, so a project running both should disable one of them.

Examples

A module declaring nine classes and four functions returns 13. A module declaring eleven closely related functions and no class returns 11. A module that only imports names and re-exports them returns 0, since nothing is declared here.

References

• Generalizes wemake-python-styleguide WPS202. Open reference
• Cites “Agile Software Development”, single responsibility principle
• Cites “A Philosophy of Software Design”, chapter 10