使用细枝宏设置变量

Question

I have to set a variable with a macro, that returns a number, so I have this macro:

{% import _self as self %}

{% macro function_size(field) %}

  {% import _self as self %}

  {# initial Setup #}
  {% set field_length = 0 %}

  {# Field #}
  {% for key, value in field %}
    {% if not (key starts with "#") %}
      {% set field_length = field_length + 1 %}
    {% endif %}
  {% endfor %}

  {{ field_length }}

{% endmacro %}

The Macro loops through the entries of a field and returns the count of values, that don't start with "#".

So I set a variable with that value:

{% set image_size       = self.function_size(content.field_teaser_image) %}

ATTENTION: With this you will set the Variable with Twig Markup. (You can see that when you debug the variable afterwards.)

To get a number/integer as value you have to convert it to a String (that will be interpreted as a number if you calculate with it)

{% set image_size       = image_size.__toString %}

With this I set the Variable successfully with a macro.

My Question: Is this a bad practice, are there better ways how to set an Variable?

Thank you!

Answer 1

Two ways to set variables for twig are fine in my opinion. 1. Use theme and other hooks (inside theme or any module) and pass variable from php, 2. create twig extension/filter

Examples:

Filter: http://leopathu.com/content/create-custom-twig-filter-drupal-8

Extension:

http://symfony.com/doc/current/templating/twig_extension.html