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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
1.3 KiB
Markdown
26 lines
1.3 KiB
Markdown
---
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bc-version: [all]
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domain: patterns
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keywords: [maxstrlen, copystr, truncation, magic-number, field-length, overflow, string]
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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 use MaxStrLen in CopyStr, never a literal length
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## Description
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When CMFRT code truncates a text value to fit a field, the length argument of `CopyStr` must be `MaxStrLen(TargetRecord.TargetField)`, never a numeric literal. The field is the single source of truth for its own length; a hardcoded number silently diverges the moment the field is widened or the code is copied to a field of a different size, producing either needless truncation or a runtime overflow error.
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## Best Practice
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Write `Rec."CMFRT AQ User ID" := CopyStr(UserId(), 1, MaxStrLen(Rec."CMFRT AQ User ID"));`. The expression stays correct through any future field-length change and documents intent: truncate to whatever fits the target.
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See sample: `cmfrt-maxstrlen-copystr.good.al`.
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## Anti Pattern
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`CopyStr(UserId(), 1, 50)` — the literal encodes the field length at the time of writing. Widening the field leaves data truncated at the stale length; narrowing it turns the assignment into a runtime "length exceeds" error that only fires on long values in production.
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See sample: `cmfrt-maxstrlen-copystr.bad.al`.
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