Template system compatibility?

[shawnbot]

There are some subtle and not-so-subtle variations in the different implementations of Django-style templates. For instance, default values in Django look like this, which is really just a holdover from Smarty:

{{ foo|default:"bar" }}

Whereas Jinja (and Nunjucks, which followed its lead) uses the function-style syntax:

{{ foo|default("bar") }}

I'm inclined to go with the Jinja syntax since Django can be made to work with Jinja templates, but not vice-versa. The goal here isn't necessarily full cross-compatibility of templates between systems, but I'd like to avoid anything proprietary to Nunjucks that would make it difficult to make a move (or at least a port) to Python, for instance, at a later date. It may also be possible to standardize on the form:

{{ foo and foo or "bar" }}

[shawnbot]

Of course, it's also possible to ignore the default and/or tertiary operator syntax altogether and just ask template authors to write:

{% if foo %}{{ foo }}{% else %}bar{% endif %}