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[ExpressionLanguage] Document precedence #19803

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homersimpsons opened this issue Apr 18, 2024 · 8 comments · Fixed by #19860
Closed

[ExpressionLanguage] Document precedence #19803

homersimpsons opened this issue Apr 18, 2024 · 8 comments · Fixed by #19860
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ExpressionLanguage hasPR A Pull Request has already been submitted for this issue.

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@homersimpsons
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Current status

The page https://symfony.com/doc/current/reference/formats/expression_language.html#supported-operators does not document operators precedence.

Objective

Add documentation about operators precedence.

Why?

Today I wanted to check the precedence of some operator in order to update a code, I had an expression that could translate to the following ambiguity:

var_dump(! null === false); // => ((!null) === false) => false
var_dump(! (null === false)); // => true

We can find the precedence in https://github.com/symfony/expression-language/blob/b8ec919a6d3d47fc4e7845c256d164413207bf73/Parser.php#L24

I think that this information should be accessible in the doc directly, but I understand that it won't benefit a lot of users so I'm wondering how it should be presented. Maybe just a collapsible array at the end, or when the precedence is mentioned in:

You must use parentheses because the unary operator not has precedence over the binary operator matches.
@94noni
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94noni commented Apr 19, 2024

A note block could be added and document this internal behavior i think yes 👍🏻

homersimpsons added a commit to homersimpsons/symfony-docs that referenced this issue May 3, 2024
@homersimpsons
Add operators precedence documentation
f6dd77e 
Closes symfony#19803
@homersimpsons homersimpsons mentioned this issue May 3, 2024
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homersimpsons added a commit to homersimpsons/symfony-docs that referenced this issue May 3, 2024
@homersimpsons
Add operators precedence documentation
f2d4f91 
Closes symfony#19803
@OskarStark
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I really like this note and we should merge it. However, what about a debug command? We have the same for listener priorities

@homersimpsons
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However, what about a debug command?

I'm not sure to understand, there is no command for symfony's expression language, right?

@OskarStark
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Yes, I would propose to create one

@homersimpsons
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What would be the purpose of such command? How do you see its interface?

@OskarStark
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I would output the list from the docs PR, if we can get the info programmatically

@javiereguiluz javiereguiluz added the hasPR A Pull Request has already been submitted for this issue. label May 9, 2024
@homersimpsons
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I would output the list from the docs PR, if we can get the info programmatically

Yes we can definitely get it programatically rather easily (minus some formating / arranging).

The repo does not have a dependency on the console component, I'm not exactly sure how to approach this. Another command I can think of would be an easy "debug" command where someone could provide an expression (and possibly variables) and get the result.

@javiereguiluz
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Given that the list of operators is very rarely updated, I'd just handle this manually.

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[ExpressionLanguage] Add operators precedence documentation homersimpsons/symfony-docs
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@javiereguiluz @OskarStark @94noni @carsonbot @homersimpsons