NotImplementedErrors should provide exception messages

[joseph@…]

The Django source has many occurrences of NotImplementedErrors raised without a message. For example, if a dev creates a class inheriting from contrib.admin.SimpleListFilter and does not provide a lookups() method, all they see from the Debug template is "NotImplementedError at /path/to/file/ No exception supplied". This, in my opinion, makes seeking help difficult for those not comfortable enough to dig through the Django source. A simple message such as "instances of SimpleListFilter must provide a lookups() method" provides instant feedback and a non-ambiguous means to seeking help if needed.

In short, my request is to have all NotImplementedError exceptions raised accompanied by a message.

I realize this change would be boring to work on, so I am more than willing to read through the patch procedures and submit a patch myself if you all find this a worthy cause. (The nature of this request may even be simple enough to send through Github)

[Tim Clifford]

Looks like gruntwork that requires a base level of code literacy, which is perfect to assign during a sprint.

I'm on it!

[Tim Clifford]

Pull request submitted and awaiting review. 92 instances of "raise NotImplementedError" used to placehold base class methods for subclassing were given verbose may/must subclass explanations, and two instances of not-implemented features were written up as well (found in /utils/datetime.py line #67 and /utils/regex_helper.py line #95).

[Tim Clifford]

Added a patch in the form of a Pull Request, visible here:
​https://github.com/django/django/pull/1569

[Tim Graham <timograham@…>]

In b2b763448f726ee952743596e9a34fcb154bdb12:

Fixed #20841 -- Added messages to NotImplementedErrors

Thanks joseph at vertstudios.com for the suggestion.