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Condition syntax sometimes evaluates the wrong branch #50

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sewi-cpan opened this issue Dec 6, 2023 · 0 comments
Open

Condition syntax sometimes evaluates the wrong branch #50

sewi-cpan opened this issue Dec 6, 2023 · 0 comments
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@slott56
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@sewi-cpan
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false ? true.exists_one(i, false) : false raises *BoolType* object is not iterable.
Expected: The first false should skip the first branch of the condition and execute the "else" branch (the last false).

The CEL language definition says:

To get traditional left-to-right short-circuiting evaluation of logical operators, as in C or other languages (also called "McCarthy Evaluation"), the expression e1 && e2 can be rewritten e1 ? e2 : false. Similarly, e1 || e2 can be rewritten e1 ? true : e2.

This error doesn't happen for false ? 1/0 : true. This condition correctly skips the division by zero.
sewi-cpan added a commit to sewi-cpan/cel-python that referenced this issue Dec 6, 2023
@sewi-cpan
Evaluate a condition branch only if needed
1d6ce96 
[The CEL language definition](https://github.com/google/cel-spec/blob/master/doc/langdef.md#logical-operators) suggests:
> To get traditional left-to-right short-circuiting evaluation of logical operators, as in C or other languages (also called "McCarthy Evaluation"), the expression e1 && e2 can be rewritten `e1 ? e2 : false`. Similarly, `e1 || e2` can be rewritten `e1 ? true : e2`.

`cel-python` used to evaluate the full tree before deciding if a branch will be used or not. This PR only evaluates a branch if selected by the condition.

Fixes issue cloud-custodian#50
@sewi-cpan sewi-cpan mentioned this issue Dec 6, 2023
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@slott56 slott56 mentioned this issue May 21, 2024
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@slott56 slott56 self-assigned this May 21, 2024
@slott56 slott56 added the bug Something isn't working label May 21, 2024
kapilt added a commit that referenced this issue Jul 24, 2024
@kapilt
fix - conditional evaluation (#50) - #63
84077d2
@glicht glicht mentioned this issue Dec 2, 2024
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Evaluate a condition branch only if needed sewi-cpan/cel-python
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@slott56 @sewi-cpan