[patch] Add template decorators

[rjwittams]

This patch includes two decorators for making template tags easier to create.

@simple_tag : 

This one is for converting functions that return a string into template tags. eg.

definition:

@simple_tag
def monkey_tag(verb):
    return "I %s no evil" % verb

use:

{% monkey_tag "hear"%}

arguments are resolved using template.resolve_variable -> ie currently limited to variable references and constant strings.

@inclusion_tag 

This decorator turns a function returning a dictionary into a template tag that renders another template inline using that dictionary as the context. The decorator takes three arguments :

• path - required path to template
• context_class - kwarg to override the default context created
• takes_context - kwarg boolean. If true, the first argument of the function must be called 'context', and the context of the calling template will be passed into this argument. Useful if it is heavily context dependent and there would be a huge number of arguments.

The point of not just using the parent context is to make it easy to tell which context variables are used in which templates, ie avoid dynamic scoping hell.

eg:

@inclusion_tag('farming/cow_detail')
def cow_display(cow):
    return {
       'name': cow.name,
       'similar': find_similar_cows(cow)
    }

template : 'farming/cow_detail'

<div>
<h2>{{name}}</h2>
<b> similar cows: </b>
{%for cow in similar %}
   <p>{{cow.name}}</p>
{% end for %}
</div>

use:

{% cow_display cow %}

[rjwittams]

patch to add template decorators

[rjwittams]

I'm not sure about the naming/location of the file. Seems like we have a lot of things called template_<something>... is that telling us something?

[Adrian Holovaty]

Yeah, we should move template-related modules into a django.core.template package, but that would be backwards-incompatible because a lot of code does from django.core.template_loader import ... and from django.core.template import ....

[rjwittams]

We could always have backwards compatibility for template_loader by just having

from template.loader import * 

in template_loader.py . Keep that around for a while but deprecate it.

and django.core.template would still work as it would be in template/init.py

or am I missing something?

[Adrian Holovaty]

Nope, you're not missing anything. :) That would do it! I think we're safe to assume nobody will have used defaultfilters, defaulttags or template_file directly.

I'll open a separate ticket.

[Adrian Holovaty]

Separate ticket filed as #626.

[rjwittams]

updated patch, moved to template/decorators.py to fit in with template reorganisation

[Adrian Holovaty]

(In [1410]) Fixed #625 -- Added template-tag decorators simple_tag and inclusion_tag. Taken from new-admin. Thanks, rjwittams