matplotlib/matplotlib — pull request #1597 by ivanov (2012-12-14 20:55:07+00:00)
Title: new MatplotlibDeprecationWarning class (against master)

It was tricky to backport this patch against v1.2.x, and since we'll want the functionality in master as well, I decided to just update the patch that I had in #1565 (it seems I can't reopen pull requests). This should be merged after #1596 is merged in v1.2.x.

In light of the fact that Python builtin DeprecationWarnings are ignored
by default as of Python 2.7 (see link below), this class was put in to
allow for the signaling of deprecation, but via UserWarnings which are
not ignored by default.

http://docs.python.org/dev/whatsnew/2.7.html#the-future-for-python-2-x

Prior to this commit:

```
In [1]: %pylab

Welcome to pylab, a matplotlib-based Python environment [backend: agg].
For more information, type 'help(pylab)'.

In [2]: mlab.liaupunov([1,2], np.diff)
Out[2]: 0.0
```

After this commit:
```
In [1]: %pylab

Welcome to pylab, a matplotlib-based Python environment [backend: agg].
For more information, type 'help(pylab)'.

In [2]: mlab.liaupunov([1,2], np.diff)
/home/pi/.local/lib/python2.7/site-packages/matplotlib/mlab.py:1212:
MatplotlibDeprecationWarning: This does not belong in matplotlib and
will be removed
mDeprecation) # 2009/06/13
Out[2]: 0.0
```