MAINT: Use __module__ in _DeprecatedModule.

[gfyoung]

Follow-up to #14105. Uses the __module__ method to correctly determine the location of the alternative
module to use.

[codecov-io]

Current coverage is 85.25% (diff: 86.66%)

Merging #14181 into master will increase coverage by 0.01%

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+ Misses         7460       7453     -7   
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[jreback]

somethings wrong. so now dir(pandas.datetools) works, but

from pandas.core.datetools import yearEnd does not show a warning

nor does tab completion on the module

In [1]: from pandas.core.datetools import /Users/jreback/miniconda/lib/python2.7/site-packages/IPython/core/completerlib.py:158: FutureWarning: The pandas.core.datetools module is deprecated and will be removed in a future ver.
  m = __import__(mod)               

                         ABCDataFrame             BDay                     BMonthEnd                businessDay              cache_readonly           CDay                     CustomBusinessHour       DateParseError            
                         ABCIndexClass            bday                     BQuarterBegin            BusinessHour             CBMonthBegin             cday                     customBusinessMonthBegin datetime                  
                         ABCSeries                bmonthBegin              BQuarterEnd              BYearBegin               cbmonthBegin             compat                   customBusinessMonthEnd   Day                      >
                         algos                    BMonthBegin              bquarterEnd              BYearEnd                 CBMonthEnd               customBusinessDay        D_RESO                   day                       

can you add some tests for this

[gfyoung]

@jreback : Did tab completion work before?

[jreback]

yes

[gfyoung]

@jreback : I couldn't get tab completion to issue a warning like that on master. Still not sure why the pandas.core.datetools import stopped issuing warnings. I think it is because I imported the module once during __init__ with a filter.

[jreback]

wel it needs to be the same as master and have the warning and have the same behavior as 0.18.1 for function

[gfyoung]

@jreback : Fair enough. I made some modifications. Can you take a look?

[jreback]

tab complete / warnings loooking good

In [1]: import pandas

In [2]: from pandas.core.datetools import C:\Anaconda\envs\pandas3.5\lib\site-packages\IPython\core\completerlib.py:158: FutureWarning: The pandas.core.datetools module is deprecated and will be removed in a future version. Please use the pandas.tseries module instead.
  m = __import__(mod)

In [3]: from pandas.core.datetools import yearEnd

In [1]: pd.datetools.yearEnd
C:\Anaconda\envs\pandas3.5\Scripts\ipython-script.py:1: FutureWarning: pandas.core.datetools.yearEnd is deprecated and will be removed in a future version.
  if __name__ == '__main__':
Out[1]: <YearEnd: month=12>

[jreback]

lgtm. @jorisvandenbossche

[jorisvandenbossche]

@gfyoung Thanks a lot!