YearOffset() raises AttributeError

[jorisvandenbossche]

From #7375 (comment):
related: #4804
xref: #7705 (MonthOffset)

In [55]: offsets.YearOffset()
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-55-b53e59b753d1> in <module>()
----> 1 offsets.YearOffset()

c:\users\vdbosscj\scipy\pandas-joris\pandas\tseries\offsets.pyc in __init__(self
, n, normalize, **kwds)
   1331
   1332     def __init__(self, n=1, normalize=False, **kwds):
-> 1333         self.month = kwds.get('month', self._default_month)
   1334
   1335         if self.month < 1 or self.month > 12:

AttributeError: 'YearOffset' object has no attribute '_default_month'

[sinhrks]

In the fix, DateOffset, MonthOffset and YearOffset should be added to pd.offsets.__all__ because test_offsets.py 's exhaustive tests target offsets included in it.

[jbrockmendel]

My understanding is that MonthOffset, YearOffset, SemiMonthOffset are base classes not indeed to be directly used. Possibly should be privatized?

[jorisvandenbossche]

My understanding is that MonthOffset, YearOffset, SemiMonthOffset are base classes not indeed to be directly used. Possibly should be privatized?

I am not familiar with offsets, but if that is the case: yes, then we should privatize them.

[jbrockmendel]

These should also be removed from the doc offset_frequency.rst file right?