Modify render_to_string to pass TEMPLATE_LOADERS the context_instance arguments

[bishanty@…]

I propose that render_to_string be modified to pass context_instance all the way down to TEMPLATE_LOADERS.

This change would allow template loaders to dynamically select a template according to the context. For example, to instrument an A/B test by checking the request in a context or to return a mobile template to a mobile user agent:

from django.template.loaders.filesystem import load_template_source as default_template_loader

def mobile_loader(template_name, template_dirs=None, context_instance=None):
    if context_instance is not None:
        if context_instance['mobile']:
            template_name = 'm' + template_name
    return default_template_loader(template_name, template_dirs, context_instance)

At the render_to_string level, this would allow you to change the rendering of most pluggable apps as well.

[Jannis Leidel]

That's already pretty easy to do with the TemplateResponse introduced in Django 1.3: ​https://docs.djangoproject.com/en/dev/releases/1.3/#templateresponse

I'm not sure why render_to_string specifically needs that ability, would you care to elaborate?