Comparison of PHPTemplate and Twig Paradigms

About Twig

Twig is a compiled template language based on PHP. When your web page is rendered, the Twig engine takes the template and converts it into a "compiled" PHP template, which is stored in a secure directory at sites/default/files/php/twig. Compilation happens once, template files are cached for reuse, and recompiled when the Twig cache is cleared.

The Drupal Twig initiative shares the same motivation as Symfony’s: to introduce a modern, powerful, object-oriented engine that allows developers to properly focus on Drupal.

1. Docblock

PHPTemplate:

Twig:

{# 
/** 
 * @file
 * File description
 */
#}

2. File and Function Names

PHPTemplate file: node--article.tpl.php
Twig file: node--article.html.twig

PHPTemplate function: THEME_node_links()
Twig file: node-links.html.twig

3. Variables

Print a variable:

PHPTemplate: <div class="content"><?php print $content; ?></div>
Twig: <div class="content">{{ content }}</div>

Print a hash key element [1]

PHPTemplate: <?php print $item['#item']['alt']; ?>
Twig: {{ item['#item'].alt }} 

Assign a variable:

PHPTemplate: <?php $custom_var = $content->comments; ?>
Twig: {% set custom_var = content.comments %}

Assign an array:

PHPTemplate: <?php $args = array('@author' => $author, '@date' => $created); ?>
Twig: {% set args = {'@author': author, '@date': created} %}

4. Conditions

PHPTemplate: <?php if ($content->comments): endif; ?>
Twig: {% if content.comments %} {% endif %}

PHPTemplate: <?php if (!empty($content->comments)): endif; ?>
Twig: {% if content.comments is not empty %} {% endif %}

PHPTemplate: <?php if (isset($content->comments)): endif; ?>
Twig: {% if content.comments is defined %} {% endif %}

PHPTemplate: <?php if ($count > 0): endif; ?>
Twig: {% if count > 0 %} {% endif %}

5. Control Structures

PHPTemplate: <?php foreach ($users as $user) {} ?>
Twig: {% for user in users %} {% endfor %}

6. Filters

Escaped HTML special characters:

PHPTemplate: <?php print check_plain($title); ?>
Twig[2]: {{ title }}

Raw output:

PHPTemplate: <?php print $title; ?>
Twig: {{ title|raw }}

Translate:

PHPTemplate: <?php print t('Home'); ?>
Twig: {{ 'Home' | t }}

Translate with substitutions:

PHPTemplate: <?php print t('Welcome, @username', array('@username' => $user->name)); ?>
Twig: {{ 'Welcome, @username'|t({ '@username': user.name }) }}

Drupal 8 Twig (with trans tag extension):

{% set username = user.name %}
{% trans %}
  Welcome, {{ username }}
{% endtrans %}

Join a list:

PHPTemplate: <?php echo implode(',', $usernames); ?>
Twig: {{ usernames|join(', ') }}

Join a list with markup:

Twig: {{ usernames|safe_join(',') }}

PHPTemplate example requires $usernames to be an array of strings. Same for the original Twig example. However, Drupal 8 Twig expects a render array. This is a fundamental difference between original Twig and Drupal 8 Twig, which can render both plain text and render arrays.

Another aspect: all examples are expected to output the same result, but they don’t (by default). Example:

  {% set numbers = [{'#markup': 'One'}, {'#markup':'Two'}, {'#markup':'Three'}] %}
  {{ numbers }}

This assumes comma separation, but the output is: OneTwoThree

7. Whitespace Control

Twig includes whitespace control to remove spacing used for template file structure.

  {{- block.content -}}

Equivalent to:

{{ block.content }}

Notes

• The hash key element example may change in the future
• Second example shows Twig handles data sanitation. Previously, the template or preprocess function handled this. For those creating PHPTemplate themes for Drupal 8, you must now sanitize your own data. ↩︎︎

For More Information:

• Twig issues in the core issue queue
• Twig conversion instructions on drupal.org
• Twig Documentation
• PHPTemplate to Twig converter script
• Twigify module for converting PHPTemplate to Twig