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afb1fa2883
- Introduced guidelines for using the "CMFRT" prefix in object names, fields, and procedures to avoid naming collisions and ensure clarity. - Established rules for object ID ranges to prevent conflicts with other extensions and maintain historical integrity. - Documented best practices and anti-patterns for various coding patterns, including case statements, interface injection, label usage, and validation methods. - Implemented a standards review skill to evaluate AL source changes against CMFRT company standards, ensuring compliance with naming, permissions, and architectural patterns.
26 lines
1.5 KiB
Markdown
26 lines
1.5 KiB
Markdown
---
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bc-version: [all]
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domain: patterns
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keywords: [case, else, defensive-coding, unhandled-case, enum, option, silent-failure]
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technologies: [al]
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countries: [w1]
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application-area: [all]
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---
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# CMFRT CASE statement requires ELSE clause
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## Description
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Every `case` statement in CMFRT AL code must include an `else` clause. The rule is unconditional: even when every currently known value of the matched expression is enumerated, the `else` clause guards against future values being added to an enum, option field, or integer range. Without `else`, a new value passes through the `case` block silently — no error, no action — and the resulting silent no-op or data corruption is difficult to trace because the `case` appears correct at the time it was written.
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## Best Practice
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Always add an `else` clause to every `case` statement. When no meaningful action applies to unexpected values, the `else` clause should raise an error that identifies the unexpected value, log it, or call a dedicated handler procedure. The key outcome is that the unexpected case is detected at runtime rather than silently ignored.
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See sample: `cmfrt-case-requires-else.good.al`.
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## Anti Pattern
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Writing a `case` statement that enumerates all currently known values and omits `else`. The code appears complete but becomes a silent failure mode the moment a new enum value is added by a future developer or by a base application update, because the added value simply falls through the entire `case` block.
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See sample: `cmfrt-case-requires-else.bad.al`.
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