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- Introduced guidelines for "one codeunit one global function" architecture to enforce single responsibility in AL code. - Added best practices and anti-patterns for adding parameters via overloads to maintain backward compatibility. - Documented the importance of never deleting members in AL and always marking them as obsolete. - Established the requirement for OnBefore and OnAfter integration events for global procedures to enhance extensibility. - Defined naming conventions for CMFRT objects, including prefixes and object ID ranges to avoid conflicts. - Implemented patterns for case statements to ensure all cases are handled, including the necessity of an else clause. - Introduced the interface injection pattern to allow pluggable operations in table-level code. - Recommended using Confirm Management for user confirmations to improve testability. - Established a three-permission set pattern for security to ensure proper access control. - Created a review skill for CMFRT AL standards to automate compliance checks against established guidelines.
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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