extends tag should compile static parents

[fredd4@…]

Extends tag compile its parents always on render. This is slowly. It should do this on init, if it is possible.

[fredd4@…]

patch for extends file

[fredd4@…]

Previous patch has a bug. Here is a good one.

[fredd4]

Caching on render works better (more correctly)

[forgems@…]

Render method for extends tag is called exactly once per template ( because only one extends tag can exist in template), so template processing is called exactly once. So your code will always call process_parent. No speed gain here.

[fredd4]

Not exactly. There is no speed gain if you use render_to_response function. But when you are using once init:

t = get_template(template_name)

and then many times render:

t.render(context_instance)

The extend tag read and parse html file every render call. It shouldn't. Extend should keep in memory parents nodes.

In my path, here you have:

if self.parent_name: 
   self.compiled_parent = compiled_parent

Let's look at my test. I render page from admin, firstly using standard extends tag, and then using my extends tag.

[fredd4]

Performance extends test

[forgems]

You can use this snippet ​http://www.djangosnippets.org/snippets/507/ to have globally enabled caching for templates. Imho it's not worth to change extends tag when you can simply monkey patch the loader system.

[fredd4]

This snippet does not fix it. Try run my test.

[forgems]

What if extends argument is a variable (changed on every request) from context. Your code will not work correctly.

[forgems]

You can pass a compiled template object as a variable to context and use as an argument for extend. You will save time for template lookup and parsing.

[fredd4]

My code will work correctly. I think, You don't check it.

If argument is variable, then it is save to variable named parent_name_expr, otherwise it is save to parent_name.
In my code, there is something like this:

if self.parent_name:
    self.compiled_parent = compiled_parent

So I check it.

[forgems]

I have cheked it and it seem ok. The only problem is when you change the parent's template code. You have to restart the server, so maybe you should change:

if self.compiled_parent:
            compiled_parent = self.compiled_parent

to

if self.compiled_parent and not settings.DEBUG:
            compiled_parent = self.compiled_parent

[Chris Beaven]

See also #6262 - a more broad way of caching templates.

[fredd4]

To cache template I use my decorator: ​http://www.djangosnippets.org/snippets/596/
But it is like Your caching using Your snippet: ​http://www.djangosnippets.org/snippets/507/

There shouldn't be settings.DEBUG, because it is cached only if you cached main template.
If you use render_to_response without modification, it never happend.

In other words, my patch works like that: if you have some template in cache, the parents are in cache too, otherwise they aren't.

It's clear?

[Carl Meyer]

This is already solved in the general case by the caching template loader - works for all template loading and compiling, not just as a special case for extends tag. So there's no need to complicate the code with a special case for extends.