https://github.com/uuf6429/expression-language-arrowfunc

➡️ Arrow function support in Symfony Expression Language
https://github.com/uuf6429/expression-language-arrowfunc

arrow-functions expression-language php symfony syntax uuf6429

Last synced: 4 months ago
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➡️ Arrow function support in Symfony Expression Language

• Host: GitHub
• URL: https://github.com/uuf6429/expression-language-arrowfunc
• Owner: uuf6429
• License: mit
• Created: 2016-10-30T02:43:24.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2022-07-20T21:40:04.000Z (almost 3 years ago)
• Last Synced: 2025-03-16T16:09:07.023Z (4 months ago)
• Topics: arrow-functions, expression-language, php, symfony, syntax, uuf6429
• Language: PHP
• Homepage:
• Size: 47.9 KB
• Stars: 3
• Watchers: 1
• Forks: 3
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Symfony Expression Language Arrow Function

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Arrow function (aka "Lambda Expression" or "Anonymous Function") support in Symfony [Expression Language component](https://symfony.com/doc/current/components/expression_language.html).

## Syntax

```

 (a) -> { a * 2 }

  ^  ^      ^

  |  |      '----- Function body is a single expression that can make use of passed parameters or global variables.

  |  '------------ The lambda operator - input parameters are to the left and the output expression to the right.

  '--------------- Comma-separated list of parameters passed to arrow function.

```

## Safety

Returning callbacks can be dangerous in PHP. If the returned value is not checked, PHP may end up executing arbitrary global functions, static class methods or object methods.

### Problem Example

```php

$language = new ExpressionLanguage();

$expression = '(value) -> { value > 20 }';

$filter = $language->evaluate($expression);

$values = array_filter([18, 23, 40], $filter);

```

If `$expression` returns a string or array, `array_filter()` will arbitrarily call whatever was returned.

### Solution

There are two solutions:

- Set the type declaration of methods using the callback to `Closure` (*not `Callable`!*) - prone to mistakes and quite risky.

- The engine returns the callback wrapped in an object that cannot be invoked by default - this is the safest option (and default one).