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63bd69d7e5
Follow-up from PR review: nested if is the right answer for two or three dependent conditions, but past that the nesting becomes the problem. AL's case statement is the flat alternative — the control statements documentation states a value set "must be an expression or a range" and that the first matching value set executes, so case true of / case false of accept boolean expressions and stop at the first match. That is the laziness the boolean operators do not provide. Adds case-true-of-for-long-condition-chains.md with good/bad AL companions: case false of for guard chains where every condition must hold, case true of for first-match dispatch. The bad sample shows both failure shapes — a five-level if ladder, and the worse escape of collapsing it into an and chain, which trades nesting for a real defect. Cross-links both articles, and adds the threshold to the short-circuit article's Best Practice so following it does not lead to a deep ladder. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
28 lines
1.1 KiB
AL
28 lines
1.1 KiB
AL
codeunit 50543 "Perf Sample CaseChain Bad"
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{
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procedure IsShippableLine(SalesLine: Record "Sales Line"): Boolean
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var
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Item: Record Item;
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begin
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// Five levels of nesting to sequence five guards. The evaluation order is
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// carried by indentation alone and the body drifts steadily right.
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if SalesLine.Type = SalesLine.Type::Item then
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if SalesLine."No." <> '' then
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if SalesLine."Qty. to Ship" > 0 then
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if Item.Get(SalesLine."No.") then
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if not Item.Blocked then
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exit(true);
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exit(false);
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end;
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procedure IsShippableLineCollapsed(SalesLine: Record "Sales Line"): Boolean
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var
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Item: Record Item;
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begin
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// The wrong escape from the ladder: flattening it into 'and' trades the
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// nesting for a defect, because every operand is still evaluated. Item
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// fields are read even when the Get failed.
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exit((SalesLine.Type = SalesLine.Type::Item) and (SalesLine."No." <> '') and
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(SalesLine."Qty. to Ship" > 0) and Item.Get(SalesLine."No.") and (not Item.Blocked));
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end;
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}
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