call explanation nunjucks/jinja

demo of call pwer

{# The field macro which accepts the configuration object and uses it #}
{% macro field(config) %}
  <div class="field-row field-row--{{ config.type | d('text') }}{{ ' field-row--' + config.size if config.size }}">
    {# the caller is then invoked and the config is passed back #}
    {% if caller %}{{ caller(config) }}{% else %}<p>Default HTML here</p>{% endif %}
  </div>
{% endmacro %}

{# calling the 'field' macro and passing in a configuration object (could be a JSON schema) #}
{%- call(config) field({ id: 'theID', type: 'password', size: 'small' }) %}
  {# as the caller we now have access here to the configuration object we originally passed in to the macro we called #}
  <input type="{{ config.type }}" name="{{ config.id }}" value="{{ config.value }}" id="{{ config.id }}">
{%- endcall %}

{# this would be the output, this is a simple example, the macro being called 
could mutate the object that was passed and return that if required #}
<div class="field-row field-row--password field-row--small">
  <input type="password" name="theID" value="" id="theID">
</div>