ALL-FUNC0007 · function_conditional_count

Limit explicit if branches inside one function or method.

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

Definition

Count every if and elif statement owned by each synchronous or asynchronous callable. Nested functions and classes start independent scopes. Return the conditional count for this callable. A separate policy can compare the value with a project ceiling such as two.

Evidence

Evidence records the callable source range and its conditional count. This intentionally narrower measurement complements cyclomatic complexity. It makes repeated type or mode switches visible even when each branch body is small. The value is the number of if and elif statements this callable owns.

Exceptions

Generated and vendored code may be excluded through globs. Guard clauses, elif branches, and nested conditionals all count because several independent decisions in one callable are still several reasons for it to change. Pattern matching and conditional expressions are not if statements and remain outside this rule.

Examples

Bad

A function that checks `BooleanPolicy`, `NumericPolicy`, and `CategoryPolicy` with three
`isinstance` branches is reported. Replace the closed type switch with one abstract operation
implemented by concrete policy or evaluator classes. When the operation cannot live on those
classes, use `functools.singledispatch` to keep type registration open to new implementations.

Good

A base ResultEvaluator.evaluate method is abstract. Boolean, numeric, and category evaluator subclasses each implement their own policy without inspecting sibling types. A function with two cohesive guard conditions remains within the default ceiling.

References

• Cites “Refactoring”, Replace Conditional with Polymorphism. Open reference
• Cites “The Python Standard Library”, functools.singledispatch. Open reference
• Cites “Clean Code”, chapter 10, Classes
• Cites “Object-Oriented Software Construction”, Open Closed Principle