How can I send variables to Jinja template from a Flask decorator?

I’m going to propose something even simpler than using a decorator or template method or anything like that:

def render_sidebar_template(tmpl_name, **kwargs):
    (var1, var2, var3) = generate_sidebar_data()
    return render_template(tmpl_name, var1=var1, var2=var2, var3=var3, **kwargs)

Yup, just a function. That’s all you really need, isn’t it? See this Flask Snippet for inspiration. It’s essentially doing exactly the same sort of thing, in a different context.