Inconsistency between AutoLocator and AutoDateLocator

[Mark531]

Bug report

Bug summary

The method tick_values() can be called directly with AutoLocator but not with AutoDateLocator.

Code for reproduction

from matplotlib.ticker import AutoLocator
l = AutoLocator()
l.tick_values(10, 20) # works

from matplotlib.dates import AutoDateLocator
import datetime

l = AutoDateLocator()
start = datetime.date(2002, 1, 5)
end = datetime.date(2003, 12, 1)
l.tick_values(start, end) # Error

Actual outcome

array([ 10.,  12.,  14.,  16.,  18.,  20.])
AttributeError: 'NoneType' object has no attribute 'get_view_interval'

Expected outcome

expect the AutoDateLocator to be independent of the axis or other graphical objects. It should be able to generate date ticks on its own.

Matplotlib version

• Operating system: Win10
• Matplotlib version: 1.5.1
• Matplotlib backend (module://ipykernel.pylab.backend_inline):
• Python version: 3.5.1
• Jupyter version (if applicable):
• Other libraries:

I'm using Anaconda (conda 4.2.9).

[dstansby]

This is expected - AutoDateLocator can't choose a specific Locator until it is associated with an axis. I'll keep this open so we can add a better error message.

[dstansby]

I think what I said above is wrong... will have a look at this issue properly soon