Macros are comparable with functions in regular programming languages. They are useful to put often used HTML idioms into reusable elements to not repeat yourself.
Here is a small example of a macro that renders a form element:
{% macro input(name, value, type, size) %}
<input type="{{ type|default('text') }}" name="{{ name }}" value="{{ value|e }}" size="{{ size|default(20) }}" />
{% endmacro %}
Macros differs from native PHP functions in a few ways:
But as with PHP functions, macros don’t have access to the current template variables.
Tip
You can pass the whole context as an argument by using the special _context variable.
Macros can be defined in any template, and need to be “imported” before being used (see the documentation for the import tag for more information):
{% import "forms.html" as forms %}
The above import call imports the “forms.html” file (which can contain only macros, or a template and some macros), and import the functions as items of the forms variable.
The macro can then be called at will:
<p>{{ forms.input('username') }}</p>
<p>{{ forms.input('password', null, 'password') }}</p>
If macros are defined and used in the same template, you can use the special _self variable to import them:
{% import _self as forms %}
<p>{{ forms.input('username') }}</p>
Warning
When you define a macro in the template where you are going to use it, you might be tempted to call the macro directly via _self.input() instead of importing it; even if seems to work, this is just a side-effect of the current implementation and it won’t work anymore in Twig 2.x.
When you want to use a macro in another macro from the same file, you need to import it locally:
{% macro input(name, value, type, size) %}
<input type="{{ type|default('text') }}" name="{{ name }}" value="{{ value|e }}" size="{{ size|default(20) }}" />
{% endmacro %}
{% macro wrapped_input(name, value, type, size) %}
{% import _self as forms %}
<div class="field">
{{ forms.input(name, value, type, size) }}
</div>
{% endmacro %}