How can I determine if a Jinja2 template block is empty?

Question

I'd like to detect if a Jinja2 template block content is empty or not. Something like this:

{% block foo %}{% endblock foo %}{% if foo %} - {% endif %}Blah Blah Blah 

What I want is conditional text outside the block definition itself. In the contrived example, I want to be able to insert a conditional string - after the block if and only if the block has been overridden and is not empty.

Is this possible?

Answer 1

Simply call the block:

{% if self.foo() %} - {% endif %}