* ``outdent()``: Outdents the generated code (see ``Twig_Node_Block`` for a
usage example).
+Creating a Twig Extension
+-------------------------
+
+The main motivation for writing an extension is to move often used code into a
+reusable class like adding support for internationalization. An extension can
+define tags, filters, tests, operators, global variables, functions, and node
+visitors.
+
+Creating an extension also makes for a better separation of code that is
+executed at compilation time and code needed at runtime. As such, it makes
+your code faster.
+
+Most of the time, it is useful to create a single extension for your project,
+to host all the specific tags and filters you want to add to Twig.
+
+.. note::
+
+ Before writing your own extensions, have a look at the Twig official
+ extension repository: http://github.com/fabpot/Twig-extensions.
+
+An extension is a class that implements the following interface::
+
+ interface Twig_ExtensionInterface
+ {
+ /**
+ * Initializes the runtime environment.
+ *
+ * This is where you can load some file that contains filter functions for instance.
+ *
+ * @param Twig_Environment $environment The current Twig_Environment instance
+ */
+ function initRuntime(Twig_Environment $environment);
+
+ /**
+ * Returns the token parser instances to add to the existing list.
+ *
+ * @return array An array of Twig_TokenParserInterface or Twig_TokenParserBrokerInterface instances
+ */
+ function getTokenParsers();
+
+ /**
+ * Returns the node visitor instances to add to the existing list.
+ *
+ * @return array An array of Twig_NodeVisitorInterface instances
+ */
+ function getNodeVisitors();
+
+ /**
+ * Returns a list of filters to add to the existing list.
+ *
+ * @return array An array of filters
+ */
+ function getFilters();
+
+ /**
+ * Returns a list of tests to add to the existing list.
+ *
+ * @return array An array of tests
+ */
+ function getTests();
+
+ /**
+ * Returns a list of functions to add to the existing list.
+ *
+ * @return array An array of functions
+ */
+ function getFunctions();
+
+ /**
+ * Returns a list of operators to add to the existing list.
+ *
+ * @return array An array of operators
+ */
+ function getOperators();
+
+ /**
+ * Returns a list of global variables to add to the existing list.
+ *
+ * @return array An array of global variables
+ */
+ function getGlobals();
+
+ /**
+ * Returns the name of the extension.
+ *
+ * @return string The extension name
+ */
+ function getName();
+ }
+
+To keep your extension class clean and lean, it can inherit from the built-in
+``Twig_Extension`` class instead of implementing the whole interface. That
+way, you just need to implement the ``getName()`` method as the
+``Twig_Extension`` provides empty implementations for all other methods.
+
+The ``getName()`` method must return a unique identifier for your extension.
+
+Now, with this information in mind, let's create the most basic extension
+possible::
+
+ class Project_Twig_Extension extends Twig_Extension
+ {
+ public function getName()
+ {
+ return 'project';
+ }
+ }
+
+.. note::
+
+ Of course, this extension does nothing for now. We will customize it in
+ the next sections.
+
+Twig does not care where you save your extension on the filesystem, as all
+extensions must be registered explicitly to be available in your templates.
+
+You can register an extension by using the ``addExtension()`` method on your
+main ``Environment`` object::
+
+ $twig = new Twig_Environment($loader);
+ $twig->addExtension(new Project_Twig_Extension());
+
+Of course, you need to first load the extension file by either using
+``require_once()`` or by using an autoloader (see `spl_autoload_register()`_).
+
+.. tip::
+
+ The bundled extensions are great examples of how extensions work.
+
+Globals
+~~~~~~~
+
+Global variables can be registered in an extension via the ``getGlobals()``
+method::
+
+ class Project_Twig_Extension extends Twig_Extension
+ {
+ public function getGlobals()
+ {
+ return array(
+ 'text' => new Text(),
+ );
+ }
+
+ // ...
+ }
+
+Functions
+~~~~~~~~~
+
+Functions can be registered in an extension via the ``getFunctions()``
+method::
+
+ class Project_Twig_Extension extends Twig_Extension
+ {
+ public function getFunctions()
+ {
+ return array(
+ 'lipsum' => new Twig_Function_Function('generate_lipsum'),
+ );
+ }
+
+ // ...
+ }
+
+Filters
+~~~~~~~
+
+To add a filter to an extension, you need to override the ``getFilters()``
+method. This method must return an array of filters to add to the Twig
+environment::
+
+ class Project_Twig_Extension extends Twig_Extension
+ {
+ public function getFilters()
+ {
+ return array(
+ 'rot13' => new Twig_Filter_Function('str_rot13'),
+ );
+ }
+
+ // ...
+ }
+
+As you can see in the above code, the ``getFilters()`` method returns an array
+where keys are the name of the filters (``rot13``) and the values the
+definition of the filter (``new Twig_Filter_Function('str_rot13')``).
+
+As seen in the previous chapter, you can also define filters as static methods
+on the extension class::
+
+$twig->addFilter('rot13', new Twig_Filter_Function('Project_Twig_Extension::rot13Filter'));
+
+You can also use ``Twig_Filter_Method`` instead of ``Twig_Filter_Function``
+when defining a filter to use a method::
+
+ class Project_Twig_Extension extends Twig_Extension
+ {
+ public function getFilters()
+ {
+ return array(
+ 'rot13' => new Twig_Filter_Method($this, 'rot13Filter'),
+ );
+ }
+
+ public function rot13Filter($string)
+ {
+ return str_rot13($string);
+ }
+
+ // ...
+ }
+
+The first argument of the ``Twig_Filter_Method`` constructor is always
+``$this``, the current extension object. The second one is the name of the
+method to call.
+
+Using methods for filters is a great way to package your filter without
+polluting the global namespace. This also gives the developer more flexibility
+at the cost of a small overhead.
+
+Overriding default Filters
+..........................
+
+If some default core filters do not suit your needs, you can easily override
+them by creating your own core extension. Of course, you don't need to copy
+and paste the whole core extension code of Twig. Instead, you can just extends
+it and override the filter(s) you want by overriding the ``getFilters()``
+method::
+
+ class MyCoreExtension extends Twig_Extension_Core
+ {
+ public function getFilters()
+ {
+ return array_merge(parent::getFilters(), array(
+ 'date' => new Twig_Filter_Method($this, 'dateFilter'),
+ // ...
+ ));
+ }
+
+ public function dateFilter($timestamp, $format = 'F j, Y H:i')
+ {
+ return '...'.twig_date_format_filter($timestamp, $format);
+ }
+
+ // ...
+ }
+
+Here, we override the ``date`` filter with a custom one. Using this new core
+extension is as simple as registering the ``MyCoreExtension`` extension by
+calling the ``addExtension()`` method on the environment instance::
+
+ $twig = new Twig_Environment($loader);
+ $twig->addExtension(new MyCoreExtension());
+
+But I can already hear some people wondering how it can work as the Core
+extension is loaded by default. That's true, but the trick is that both
+extensions share the same unique identifier (``core`` - defined in the
+``getName()`` method). By registering an extension with the same name as an
+existing one, you have actually overridden the default one, even if it is
+already registered::
+
+ $twig->addExtension(new Twig_Extension_Core());
+ $twig->addExtension(new MyCoreExtension());
+
+Tags
+~~~~
+
+Adding a tag in an extension can be done by overriding the
+``getTokenParsers()`` method. This method must return an array of tags to add
+to the Twig environment::
+
+ class Project_Twig_Extension extends Twig_Extension
+ {
+ public function getTokenParsers()
+ {
+ return array(new Project_Set_TokenParser());
+ }
+
+ // ...
+ }
+
+In the above code, we have added a single new tag, defined by the
+``Project_Set_TokenParser`` class. The ``Project_Set_TokenParser`` class is
+responsible for parsing the tag and compiling it to PHP.
+
+Operators
+~~~~~~~~~
+
+The ``getOperators()`` methods allows to add new operators. Here is how to add
+``!``, ``||``, and ``&&`` operators::
+
+ class Project_Twig_Extension extends Twig_Extension
+ {
+ public function getOperators()
+ {
+ return array(
+ array(
+ '!' => array('precedence' => 50, 'class' => 'Twig_Node_Expression_Unary_Not'),
+ ),
+ array(
+ '||' => array('precedence' => 10, 'class' => 'Twig_Node_Expression_Binary_Or', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+ '&&' => array('precedence' => 15, 'class' => 'Twig_Node_Expression_Binary_And', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+ ),
+ );
+ }
+
+ // ...
+ }
+
+Tests
+~~~~~
+
+The ``getTests()`` methods allows to add new test functions::
+
+ class Project_Twig_Extension extends Twig_Extension
+ {
+ public function getTests()
+ {
+ return array(
+ 'even' => new Twig_Test_Function('twig_test_even'),
+ );
+ }
+
+ // ...
+ }
+
+.. _`spl_autoload_register()`: http://www.php.net/spl_autoload_register
.. _`rot13`: http://www.php.net/manual/en/function.str-rot13.php
+++ /dev/null
-Creating a Twig Extension
-=========================
-
-The main motivation for writing an extension is to move often used code into a
-reusable class like adding support for internationalization. An extension can
-define tags, filters, tests, operators, global variables, functions, and node
-visitors.
-
-Creating an extension also makes for a better separation of code that is
-executed at compilation time and code needed at runtime. As such, it makes
-your code faster.
-
-Most of the time, it is useful to create a single extension for your project,
-to host all the specific tags and filters you want to add to Twig.
-
-.. note::
-
- Before writing your own extensions, have a look at the Twig official
- extension repository: http://github.com/fabpot/Twig-extensions.
-
-An extension is a class that implements the following interface::
-
- interface Twig_ExtensionInterface
- {
- /**
- * Initializes the runtime environment.
- *
- * This is where you can load some file that contains filter functions for instance.
- *
- * @param Twig_Environment $environment The current Twig_Environment instance
- */
- function initRuntime(Twig_Environment $environment);
-
- /**
- * Returns the token parser instances to add to the existing list.
- *
- * @return array An array of Twig_TokenParserInterface or Twig_TokenParserBrokerInterface instances
- */
- function getTokenParsers();
-
- /**
- * Returns the node visitor instances to add to the existing list.
- *
- * @return array An array of Twig_NodeVisitorInterface instances
- */
- function getNodeVisitors();
-
- /**
- * Returns a list of filters to add to the existing list.
- *
- * @return array An array of filters
- */
- function getFilters();
-
- /**
- * Returns a list of tests to add to the existing list.
- *
- * @return array An array of tests
- */
- function getTests();
-
- /**
- * Returns a list of functions to add to the existing list.
- *
- * @return array An array of functions
- */
- function getFunctions();
-
- /**
- * Returns a list of operators to add to the existing list.
- *
- * @return array An array of operators
- */
- function getOperators();
-
- /**
- * Returns a list of global variables to add to the existing list.
- *
- * @return array An array of global variables
- */
- function getGlobals();
-
- /**
- * Returns the name of the extension.
- *
- * @return string The extension name
- */
- function getName();
- }
-
-To keep your extension class clean and lean, it can inherit from the built-in
-``Twig_Extension`` class instead of implementing the whole interface. That
-way, you just need to implement the ``getName()`` method as the
-``Twig_Extension`` provides empty implementations for all other methods.
-
-The ``getName()`` method must return a unique identifier for your extension.
-
-Now, with this information in mind, let's create the most basic extension
-possible::
-
- class Project_Twig_Extension extends Twig_Extension
- {
- public function getName()
- {
- return 'project';
- }
- }
-
-.. note::
-
- Of course, this extension does nothing for now. We will customize it in
- the next sections.
-
-Twig does not care where you save your extension on the filesystem, as all
-extensions must be registered explicitly to be available in your templates.
-
-You can register an extension by using the ``addExtension()`` method on your
-main ``Environment`` object::
-
- $twig = new Twig_Environment($loader);
- $twig->addExtension(new Project_Twig_Extension());
-
-Of course, you need to first load the extension file by either using
-``require_once()`` or by using an autoloader (see `spl_autoload_register()`_).
-
-.. tip::
-
- The bundled extensions are great examples of how extensions work.
-
-Globals
--------
-
-Global variables can be registered in an extension via the ``getGlobals()``
-method::
-
- class Project_Twig_Extension extends Twig_Extension
- {
- public function getGlobals()
- {
- return array(
- 'text' => new Text(),
- );
- }
-
- // ...
- }
-
-Functions
----------
-
-Functions can be registered in an extension via the ``getFunctions()``
-method::
-
- class Project_Twig_Extension extends Twig_Extension
- {
- public function getFunctions()
- {
- return array(
- 'lipsum' => new Twig_Function_Function('generate_lipsum'),
- );
- }
-
- // ...
- }
-
-Filters
--------
-
-To add a filter to an extension, you need to override the ``getFilters()``
-method. This method must return an array of filters to add to the Twig
-environment::
-
- class Project_Twig_Extension extends Twig_Extension
- {
- public function getFilters()
- {
- return array(
- 'rot13' => new Twig_Filter_Function('str_rot13'),
- );
- }
-
- // ...
- }
-
-As you can see in the above code, the ``getFilters()`` method returns an array
-where keys are the name of the filters (``rot13``) and the values the
-definition of the filter (``new Twig_Filter_Function('str_rot13')``).
-
-As seen in the previous chapter, you can also define filters as static methods
-on the extension class::
-
-$twig->addFilter('rot13', new Twig_Filter_Function('Project_Twig_Extension::rot13Filter'));
-
-You can also use ``Twig_Filter_Method`` instead of ``Twig_Filter_Function``
-when defining a filter to use a method::
-
- class Project_Twig_Extension extends Twig_Extension
- {
- public function getFilters()
- {
- return array(
- 'rot13' => new Twig_Filter_Method($this, 'rot13Filter'),
- );
- }
-
- public function rot13Filter($string)
- {
- return str_rot13($string);
- }
-
- // ...
- }
-
-The first argument of the ``Twig_Filter_Method`` constructor is always
-``$this``, the current extension object. The second one is the name of the
-method to call.
-
-Using methods for filters is a great way to package your filter without
-polluting the global namespace. This also gives the developer more flexibility
-at the cost of a small overhead.
-
-Overriding default Filters
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-If some default core filters do not suit your needs, you can easily override
-them by creating your own core extension. Of course, you don't need to copy
-and paste the whole core extension code of Twig. Instead, you can just extends
-it and override the filter(s) you want by overriding the ``getFilters()``
-method::
-
- class MyCoreExtension extends Twig_Extension_Core
- {
- public function getFilters()
- {
- return array_merge(parent::getFilters(), array(
- 'date' => new Twig_Filter_Method($this, 'dateFilter'),
- // ...
- ));
- }
-
- public function dateFilter($timestamp, $format = 'F j, Y H:i')
- {
- return '...'.twig_date_format_filter($timestamp, $format);
- }
-
- // ...
- }
-
-Here, we override the ``date`` filter with a custom one. Using this new core
-extension is as simple as registering the ``MyCoreExtension`` extension by
-calling the ``addExtension()`` method on the environment instance::
-
- $twig = new Twig_Environment($loader);
- $twig->addExtension(new MyCoreExtension());
-
-But I can already hear some people wondering how it can work as the Core
-extension is loaded by default. That's true, but the trick is that both
-extensions share the same unique identifier (``core`` - defined in the
-``getName()`` method). By registering an extension with the same name as an
-existing one, you have actually overridden the default one, even if it is
-already registered::
-
- $twig->addExtension(new Twig_Extension_Core());
- $twig->addExtension(new MyCoreExtension());
-
-Tags
-----
-
-Adding a tag in an extension can be done by overriding the
-``getTokenParsers()`` method. This method must return an array of tags to add
-to the Twig environment::
-
- class Project_Twig_Extension extends Twig_Extension
- {
- public function getTokenParsers()
- {
- return array(new Project_Set_TokenParser());
- }
-
- // ...
- }
-
-In the above code, we have added a single new tag, defined by the
-``Project_Set_TokenParser`` class. The ``Project_Set_TokenParser`` class is
-responsible for parsing the tag and compiling it to PHP.
-
-Operators
----------
-
-The ``getOperators()`` methods allows to add new operators. Here is how to add
-``!``, ``||``, and ``&&`` operators::
-
- class Project_Twig_Extension extends Twig_Extension
- {
- public function getOperators()
- {
- return array(
- array(
- '!' => array('precedence' => 50, 'class' => 'Twig_Node_Expression_Unary_Not'),
- ),
- array(
- '||' => array('precedence' => 10, 'class' => 'Twig_Node_Expression_Binary_Or', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
- '&&' => array('precedence' => 15, 'class' => 'Twig_Node_Expression_Binary_And', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
- ),
- );
- }
-
- // ...
- }
-
-Tests
------
-
-The ``getTests()`` methods allows to add new test functions::
-
- class Project_Twig_Extension extends Twig_Extension
- {
- public function getTests()
- {
- return array(
- 'even' => new Twig_Test_Function('twig_test_even'),
- );
- }
-
- // ...
- }
-
-.. _`spl_autoload_register()`: http://www.php.net/spl_autoload_register
projects / web/konrad/twig.git / commitdiff