bcquality/microsoft/knowledge/style/al-comments-must-not-restate-what-code-already-shows.md
Michael Dieringer 67962727f6 Fix ten focused correctness items plus sample links from Jesper's 2026-09-15 re-review
Six carried-over threads:
- api-page-least-privilege-write-access fixtures: added the mandatory
  EntityName/EntitySetName properties (AL0485).
- pages-must-not-contain-business-logic fixtures: Sales Line has no
  "Total Amount" field; replaced with the real "Line Amount" (field 103).
- test-feature-scenario-tags.good.al and test-one-when-per-test.good.al:
  CreatePriceHeader leaves a price list in Draft status, which price
  calculation ignores. Added Validate(Status, Active) + Modify before the
  sales line that depends on it. Verified Status field/enum against
  PriceListHeader.Table.al and PriceStatus.Enum.al in the BCApps clone.
- exposed-objects-must-be-in-a-permission-set.md: a published codeunit is
  a SOAP endpoint (SOAP is deprecated), not OData - Page/Query are the
  OData object types. Corrected and pointed new integrations at API
  pages/queries instead.
- al-error-handling-review.md: the log-writes-must-survive-rollback cue
  selected on Session.StartSession, which only appears in the compliant
  fix, never in the anti-pattern - the bad fixture could never be
  worklisted. Recued on the actual risk shape (log insert around a
  failed TryFunction/GetLastError* path, then raise/propagate), with
  StartSession as an explicit compliant discriminator instead.
- page-design-must-match-bc-page-type-conventions.md: the enum value is
  NavigatePage, not Navigate; noted the type list is a selected subset,
  not an exhaustive PageType catalogue (PromptDialog, ConfigurationDialog,
  UserControlHost, XmlPort also exist, out of this article's scope).

Four new correctness gaps:
- release-must-update-app-version.md: "the version is the only identity"
  was backwards - id is the app's stable identity, version identifies a
  release/code-state of it.
- defensive-vs-offensive-code-must-match-blast-radius.good.al: the "low
  blast radius" example had no else branch, so a failed Customer.Get()
  left the field at its prior/default value instead of the explicit
  chosen fallback the article claims to demonstrate. Added the else.
- bcpt-scenarios-must-be-app-specific.good.al: InitTest and both measured
  StartScenario/EndScenario sections were empty/comment-only, so the
  "app-specific" fixture measured no actual work. Filled in a real,
  self-contained header+line creation path.
- upgrade-tag-logic-must-not-nest-deeply.good.al: the flattened version
  dropped both safety conditions the bad fixture had (Discount % = 0,
  nonblank posting group), silently changing behavior instead of just
  removing nesting. Extracted the guarded update into a helper with both
  conditions preserved as early exits.

Also converted this PR's remaining plain-backtick "See sample:" sample
references (16 articles) to the READ-convention markdown-link form,
matching the fix already made on #156/#158.

Rebased onto upstream/main (conflicts in al-ui-review.md, al-style-review.md,
al-upgrade-review.md against merged upstream PRs - all additive, both
sides' worklist cues retained).
2026-09-21 22:44:17 +02:00

1.7 KiB

bc-version domain keywords technologies countries application-area
all
style
comments
verbosity
self-documenting
restate
tutorial-style
al
w1
all

Comments must not restate what the code already shows

Description

A comment above nearly every statement that just narrates what the statement already says (// Validate the customer number above SalesHeader.Validate("Sell-to Customer No.", CustomerNo)) adds noise without adding information. Production AL — the Base Application, mature partner codebases — is comment-sparse by comparison: identifiers do the explaining, and a comment appears only when the code alone can't carry the reason.

A comment earns its place only when it captures something the code cannot: a non-obvious business rule, a workaround for a specific platform limitation, or a constraint that would surprise the next reader. If removing the comment would leave the reader no worse off, the comment should not have been written.

This does not override required structural documentation — feature/scenario test tags and XML-doc summaries on public library procedures remain required where they apply; those are structural markers, not narrative comments.

Best Practice

Let the code speak for itself; reserve comments for the reason a reader could not otherwise infer.

See sample: al-comments-must-not-restate-what-code-already-shows.good.al.

Anti Pattern

A comment line before every statement, repeating in English what the statement's own identifiers already say.

See sample: al-comments-must-not-restate-what-code-already-shows.bad.al.