How to use variables in templatetags?

[good-idea]

Specifically, I'm trying to supply a dynamic argument to Django's template fragment caching templatetag:

{% load cache %}
{% cache 500 sidebar request.user.username %}
    .. sidebar for logged in user ..
{% endcache %}

I've tried all of the methods of interpolation here, but it always ends up taking the whole thing literally. For example:

- cache sidebar {{request.user.username}}
// u('template.cache.{{request.user.username}}.d41d7c....
- cache sidebar #{request.user.username}
// u('template.cache.#{request.user.username}.d41d7c....

Is it possible to include variables here? Is this a simple Jade thing that I'm missing, an issue with Django, or pyjade?

[good-idea]

Closing this, nevermind -- - cache sidebar request.user.username works as expected: you just don't see the username in the cache tab of the Django toolbar.