Nested If

ID

python.nested_if

Severity

low

Remediation Complexity

medium

Remediation Risk

low

Remediation Effort

medium

Resource

Complexity

Language

Python

Tags

complexity

Description

Reports an if statement whose nesting depth exceeds a configurable threshold (default 4). Deep nesting hides the actual control flow under indentation; the same logic almost always reads better as a chain of guard clauses or a dispatch dict.

def classify(x):
    if x > 0:
        if x > 10:
            if x > 100:
                if x > 1000:
                    if x > 10000:    # FLAW (depth 5 with limit 4)
                        return "huge"

elif chains do not deepen the nest — they are sequential branches of the surrounding if.

Configuration

maxDepth (default 4): maximum allowed nesting depth.

Rationale

Past depth 4, readers cannot keep the entry conditions in working memory and the function becomes a bug magnet. A guard-clause refactor or a dispatch dict almost always restores readability.

Remediation

  • Replace nested if-chains with early returns / guard clauses.

  • Extract inner branches into helper functions.

  • Replace value-dispatch chains with a dict lookup.

References