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wachterjohanneswachterjohannes/symfony-skills/skills/make-twig-extension/SKILL.md

make-twig-extension

Skill4 starsChanged 2 months agoMITView on GitHub

Use when a template needs a filter or function that Twig does not provide.

The file

We split this skill into the rules it gives an agent

1 rule. About 0 are common, 0 are distinctive, and 1 is very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈0

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 1

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Very specific:

    Check that Twig or Symfony does not already cover it.

    line 21

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Twig extension

symfony console make:twig-extension AppExtension

The maker takes the class name as an argument and asks nothing further. Install it first if it is missing: symfony composer require --dev symfony/maker-bundle.

Before writing one

Check that Twig or Symfony does not already cover it. format_currency, format_datetime, u from the String component, and the serializer extension between them cover most of what people write extensions for. symfony console debug:twig lists everything currently available, filters and functions included.

What to keep

Since maker-bundle 1.68 the extension is a single class. Each filter or function is a method marked #[AsTwigFilter('name')] or #[AsTwigFunction('name')]. There is no getFilters() list, no separate runtime class, and nothing to register: the attributes do all of it, and Twig still instantiates the class only when a template calls one of its names. Do not reintroduce the old AbstractExtension shape.

A filter that produces safe HTML declares it, otherwise its output gets escaped: #[AsTwigFilter('name', isSafe: ['html'])].

Presentation logic only. A filter that queries the database has moved business logic into the template layer.

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