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NASA Power of 10 Rule 4 — Functions ≤60 lines (one printed page). Severity: high.
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Based on SOC occupation classification
NASA Power of 10 Rule 1 — Restrict control flow to simple constructs (no goto, setjmp/longjmp, recursion). Severity: blocker.
NASA Power of 10 Rule 2 — Every loop must have a statically determinable upper bound. Severity: blocker.
NASA Power of 10 Rule 3 — No dynamic memory allocation after initialization. Severity: blocker.
NASA Power of 10 Rule 5 — Average ≥2 runtime assertions per function. Severity: high.
NASA Power of 10 Rule 6 — Declare data at smallest possible scope. Severity: medium.
NASA Power of 10 Rule 7 — Check every non-void return value; validate every parameter. Severity: blocker.
| name | pow10-rule-04-short-functions |
| description | NASA Power of 10 Rule 4 — Functions ≤60 lines (one printed page). Severity: high. |
Severity: high
Each function fits on one printed page — hard limit 60 source lines (excluding comments), soft limit 40. Functions exceeding the hard limit must be decomposed or carry a documented waiver.
A function that fits on one page can be reviewed and tested as a unit. Longer functions hide bugs by combining responsibilities. Short functions also make refactoring safer and unit testing tractable.
if/for)Extract by responsibility. Each helper takes one phase of the work and returns its output to the caller, which now reads as a sequential pipeline. Each helper is independently testable.
Generated code, large switch dispatchers (consider table-driven instead), state machines. Document with a waiver:
// pow10: allow rule=4 until=YYYY-MM-DD owner=<handle> reason="generated state table"