Patch to add subviews for template tags

[gch@…]

In django/template/__init__.py, there exists a special tag function for performing common inclusion tasks, basically to insert the output of another template into a given template.

This is quite useful, but in most cases it'd be better for a template tag to call a python function rather than just inserting another template. I took the code for inclusion_tag, and created a new tag function, subview_tag, which instead uses a python function to generate content for a template tag. Like inclusion_tag, it is allowed to take the context and just pass it along.

In my case, I use subview_tags to be able to write custom tags in templates that end up doing rather complex tasks in python, without having to go through the normal hassle.

Here's an example of using subview_tag:

# Subview function
def my_subview(context, some_argument):
    return "This is an example page, with an argument %s" % some_argument

# register a new syntax tag: {% view my_argument %}
register.subview_tag('view', takes_context=True)(my_subview)

[gch@…]

Oops. Mismarked category.

[Malcolm Tredinnick]

This doesn't seem to add anything you can't already do with either inclusion_tag() -- since you can execute as much Python code as you like inside your function there -- or, more generally simple_tag() after we fix #1105.

[gch@…]

Just a note. Inclusion tag ONLY allows you to insert other templates within a given template, so no, inclusion_tag is not a suitable replacement for the problem that subview_tag tries to solve.

But yes, it looks like #1105 does also solve this problem, so I'll hope that that solution gets rolled in sometime.