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TwigEdit

Twig is a templating engine for the PHP programming language that has become a staple in modern web development. Created by Fabien Potencier of SensioLabs, it is best known as the default templating engine in the Symfony framework, though it is widely used beyond that ecosystem. Twig compiles templates into optimized PHP code, enabling a clean separation between presentation and business logic while delivering fast rendering performance. Its design draws on ideas from Jinja2, the templating language from the Python world, and emphasizes readability, security, and extensibility. The project is typically distributed as a standalone library and can be integrated with a variety of PHP applications, including Drupal for theming and, via bridges, other frameworks in the PHP landscape.

Overview

  • Syntax and constructs
    • Twig templates use {{ expression }} to output values and {% ... %} for control structures such as conditionals and loops. This separation of syntax from content helps keep templates readable and maintainable. The engine provides a rich set of operators and functions that can be used inside expressions, and it supports custom extensions to add domain-specific capabilities. See Template language for a broader discussion of templating concepts, and Twig for the engine itself.
  • Template inheritance and composition
    • A core feature is template inheritance, enabling a base template to define blocks that child templates can override. This is expressed with {% extends 'base.html.twig' %} and {% block name %}...{% endblock %}. The mechanism promotes consistency across pages and reduces duplication, a pattern that is widely adopted in Symfony applications and other large projects.
  • Filters, functions, and tests
    • Output can be transformed with filters such as |escape (often abbreviated as |e) to prevent cross-site scripting, or |upper, |lower, and many others. Functions and tests add expressive power—for example, is defined, length, in, and custom filters or tests provided by extensions. These features allow templates to stay declarative while relying on the underlying application for data logic.
  • Security mechanisms
    • Twig emphasizes secure rendering through auto-escaping by default in many environments, a feature that mitigates common web vulnerabilities. It also offers a sandbox mode to restrict what template code can do, which is important when templates are sourced from user input or integrated into larger, potentially untrusted systems. See Security (computing) and Sandbox (security) for related concepts.
  • Environment, loaders, and caching
    • The runtime context is the Twig Environment, which configures rendering behavior, available extensions, and the template loader. Loaders determine where templates come from, with examples including FileSystemLoader and ArrayLoader. Twig compiles templates to PHP and caches the generated code to speed up repeated renders, a key factor in its performance profile.
  • Internationalization and debugging
    • Internationalization can be supported through translation extensions, enabling templates to render locale-aware text. Debugging facilities, such as variable dumps and profiler integrations, help developers diagnose rendering behavior without embedding logic into templates.
  • Ecosystem and usage
    • In the Drupal project, Twig has become the standard for theming since Drupal 8, replacing older PHP-based templating approaches. In the Symfony ecosystem, Twig is deeply integrated and often preferred for its expressive syntax and strong tooling. There are also community-driven bridges and adapters that allow Twig to be used with other PHP frameworks, including Laravel via packages such as TwigBridge and related projects. The broader PHP community has contributed a wide range of extensions and integrations, reflecting Twig’s role as a versatile templating option across many kinds of web projects. Related tools and concepts include PHP templating patterns, template engine, and the evolution of front-end and back-end separation in web development.

History

Twig originated as an expressive alternative to earlier PHP templating approaches, aiming to provide a safer and more readable syntax while keeping templates decoupled from application logic. Its development paralleled the growth of the Symfony framework, and its design has been influenced by the templating styles found in Jinja2 and other mature templating systems. Over time, Twig matured into a stable, widely adopted component of the PHP ecosystem, with major versions delivering improved performance, richer extensions, and stronger security guarantees. The project maintains compatibility with existing templates while expanding capabilities to support modern web development needs.

Architecture and design principles

  • Separation of concerns
    • Twig enforces a clear division between template presentation and application code, helping teams reduce coupling and improve maintainability.
  • Readability and safety
    • The syntax prioritizes legibility, and the default escaping behavior reduces inadvertent security flaws without requiring ad hoc boilerplate in every template.
  • Extensibility
    • The architecture supports custom filters, tests, functions, and tags through a well-defined extension mechanism, enabling teams to tailor Twig to their domain models and data sources.
  • Performance
    • By compiling templates into native PHP and caching the results, Twig minimizes runtime interpretation overhead and scales well for high-traffic sites.

See also