Can we name this "requirements"?

Probably don't need these comments, since the exception name is self-explanatory.

Same here.

Same here.

Combine these.

Separate paragraphs by a blank comment line.

I think the original formatting is fine, as that's the standard way it's done with Django urls.py files.

Can you add documentation to these classes?

Since we're just reusing the default constructor, these can just be:

class EnablingExtensionError(Exception):
    pass

These extra blank lines should be removed.

Multi-line comments should be in this form:

/*
 * Comment line 1
 * Comment line 2
 */

Also, this comment will be repeated per-extension. It should be moved out before the for loop.

This should use ?{{MEDIA_SERIAL}}

Same here.

No spaces within the {{..}}

This might be better as a filter, so we can do:

{% if extension|has_disabled_requirements %}

This shouldn't say what value it returns specifically in the summary. More like: "Returns whether or not an extension has one or more disabled requirements."

All CSS rules should be alphabetized.

Should use the:

/*
 *
 */

format.

Where does 'error_message' come from?

I prefer not to have words like "can't" in a name. Maybe "ENABLE_EXTENSION_FAILED" and "DISABLE_EXTENSION_FAILED"

Constructor initialization should be first.

Also, should user super() to initialize the parent class.

Try formatting it like:

ext_class = self.extension_manager.get_installed_extension(
    registered_extension.class_name)

Doesn't enable_extension take care of this? If the problem is that our version is stale, then we should just re-fetch it on returning it, instead of faking the value.

Can you re-pull and merge your branches and update this? It seems to include bits of other changes.

Otherwise, looks good to me. I'll commit it once there's an updated patch.

test

This patch is available here:  http://github.com/mikeconley/djblets/commits/rr1618_extension_enabling_disabling_api

Committed to extensions as cae5217.