Difference between jinja2 functions and filters?

Question

I am writing some functions to do things like format dates and text in my templates.

def coolfunc(s):
    return s + ' is cool'

 app.jinja_env.globals.update(coolfunc=coolfunc)
 app.jinja_env.filters['coolfunc'] = coolfunc

template:

{{ coolfunc(member.name) }}
{{ member.name | coolfunc }}

output:

John is cool
John is cool

I am not sure what the real difference between functions and filters are. It seems to me that filters just look cleaner?

Answer 1

The difference is that filters can have special access to the Environment or Context, but regular (global) functions cannot; specifically, there's contextfilter and friends. This can be useful for doing context sensitive things like localization and formatting, without depending on global state.

http://jinja.pocoo.org/docs/api/#utilities