code-comments

name	code-comments
description	Comment style for the Charty codebase — use when writing or editing any Kotlin in charty/ or composeApp/, and before committing. This codebase is self-documenting: essentially no inline `//` comments. Do NOT add comments that restate what the code, a name, or a test already says (e.g. `LineChartConfig() // must not throw`, `if (x == 0) return // guard`). Keep KDoc; drop inline noise.

Code comments

Charty is written to read without inline commentary: clear names, small functions, and KDoc on public declarations. Match that. The bar for adding an inline // comment is very high.

Rule

Do not add inline // comments. Before writing one, assume it should not exist. The codebase has almost none, and they read as noise against that style.

Never write a comment that restates what the code, a symbol name, or a test name already conveys. These are all banned:

LineChartConfig()               // must not throw          ← the test name already says this
if (range == 0f) return          // guard against zero range ← the code already says this
val brush = Brush.linearGradient(color.value) // create brush ← restates the call
values.filter { it > 0f }        // keep positives           ← restates the call
// regression: ...                                          ← put context in the test name instead

Instead, encode the intent where it belongs:

• What / behaviour → a good function or variable name, or a descriptive @Test name (fromMinValue_negativeBar_growsUpward).
• Non-obvious rationale (a real "why") → the function's KDoc, not an inline comment. If a guard or fallback exists for a subtle reason (overflow, a Compose phase, a platform quirk), state it in the KDoc of the function that contains it.

Applying it

• When you catch yourself about to write //, first try to rename something or add/extend KDoc.
• When editing existing code, remove inline // comments that only restate the code — but keep:
  • KDoc (/** … */) and its @param/@property/@return tags,
  • license/copyright headers,
  • comments inside KDoc ```kotlin examples (they document the example),
  • // TODO/// FIXME that track real outstanding work.
• This is a commit gate: a diff that adds inline // comments restating the code is not ready. commit-with-stats checks for it.

Quick self-check on a staged diff:

git diff --cached -U0 -- '*.kt' | grep -E '^\+' | grep -E '//' | grep -vE '/\*\*|^\+\s*\*|https?://|TODO|FIXME'

Every line it prints should be justified as a real "why" that could not live in a name or KDoc — otherwise delete the comment.