bcquality/microsoft/knowledge/style/use-this-keyword-in-codeunits.md
Jesper Schulz-Wedde e570d6113f Extract 55 knowledge articles from BC review-agent prompt
Adds 55 articles (plus 76 code samples) spanning four new domains and
two existing domains, extracted from the internal Business Central
review-agent prompt. Content was filtered against BCQuality's
remedial-knowledge premise: each article encodes BC-specific behaviour,
a CodeCop rule, a platform API semantic, or an anti-false-positive
guideline that a capable LLM would otherwise get wrong.

New domains:
- privacy (11 articles): DataClassification inheritance semantics, the
  StrSubstNo-defeats-Error-telemetry-classification pitfall, Privacy
  Notice consent for outgoing requests, anti-false-positives for pages
  and in-memory data.
- upgrade (11 articles): upgrade-codeunit structure, upgrade-tag
  lifecycle and registration, protected DB reads, DataTransfer for
  large datasets, InitValue semantics, enum-ordinal preservation,
  obsolete-workflow, first-install detection.
- ui (9 articles): caption capitalization by phrase type, tooltip voice,
  teaching-tip vs tooltip, tour-tip conventions, character limits,
  banned terms, ampersand handling, title punctuation.
- style (11 articles): label-suffix convention, API page naming,
  temporary-variable prefix, label properties (Comment/Locked), named
  invocations, FieldCaption in user messages, OptionCaption pairing,
  Error-parameter passing, `this` keyword, required parentheses, file
  naming.

Gaps in existing domains:
- performance (11 articles): production-scale table catalog (no row
  counts, per internal-data concern), anti-false-positive for bounded
  tables, guard-before-Get ordering, redundant-Get-in-OnAfterGetRecord,
  LockTable in read-only helpers, combined ModifyAll passes, writes in
  OnAfterGetRecord, SetLoadFields heuristics, temporary-table
  regressions, FlowField source-table widening, MaintainSQLIndex
  disabling SIFT.
- security (2 articles): environment-specific hardcoded GUIDs,
  ValidateTableRelation=false on user input.

Intentionally excluded: specific production P95 row-count numbers
(aggregated internal telemetry); rewritten as categorical guidance on
which tables to treat as production-scale without publishing sizes.

All articles use `bc-version: [all]` (applies to every BC version, per
the new schema sentinel). Validator passes with 0 errors / 0 warnings.
2026-04-23 16:43:42 +02:00

1.6 KiB

bc-version domain keywords technologies countries application-area
all
style
this
codeunit
self-reference
aa0248
readability
al
w1
all

Use the this keyword for codeunit self-reference

Description

CodeCop rule AA0248 recommends the this keyword inside codeunit procedures when referring to the codeunit's own members or passing the codeunit itself to another procedure. AL's scope resolution otherwise blurs global-variable access, local-variable access, and same-codeunit method calls into the same unqualified syntax — a reader of ValidateCustomer(Customer) cannot tell at the call site whether ValidateCustomer is a local, a global, or a method on a different codeunit in scope. this.ValidateCustomer(Customer) removes the ambiguity, and OtherCodeunit.DoWork(this) is the only way to pass the current codeunit as a parameter.

Best Practice

In codeunits, prefix same-codeunit method calls with this. when the call is ambiguous or when the scope spans more than a few lines. When the current codeunit needs to be passed as an argument, write this — there is no alternative syntax. The rule applies to codeunits; pages, reports, and tables have their own scoping.

See sample: use-this-keyword-in-codeunits.good.al.

Anti Pattern

ValidateCustomer(Customer); SomeOtherCodeunit.DoWork(/* this codeunit? */); — the first call has ambiguous origin, and the second cannot pass the current codeunit without this. The style becomes load-bearing as the codeunit grows past a few small procedures.

See sample: use-this-keyword-in-codeunits.bad.al.