NumPy currently makes extensive use of the DeprecationWarning class to alert users when some feature is going to be withdrawn. However, as of Python 2.7, the DeprecationWarning is silent by default, see:
This makes sense to me for deprecation warnings from Python itself or the standard library - after all, Python 2.7 is the last of the Python 2.x series.
However, I believe that a silent DeprecationWarning is bad news for third party libraries like NumPy where many end users are coders and we want them to see these warnings by default. Is anyone else concerned about this? A typical NumPy user (on Python 2.7+ or Python 3.2+) may never see the warnings (because they have to deliberately turn them on), the first they'll know about it is when they upgrade to a new release and their code suddenly stops working.
Potentially NumPy would have to introduce its own NumPy specific DeprecationWarning warning class, and use that.