DOC: use substitution decorator for business month classes (pandas-dev#25828)

Author: abatisse

pandas/tseries/offsets.py

@@ -1,26 +1,24 @@
 # -*- coding: utf-8 -*-
-from datetime import date, datetime, timedelta
 import functools
 import operator
+from datetime import date, datetime, timedelta
 
-from dateutil.easter import easter
 import numpy as np
+from dateutil.easter import easter
+from pandas._libs.tslibs.offsets import (
+    ApplyTypeError, BaseOffset, _get_calendar, _is_normalized, _to_dt64,
+    apply_index_wraps, as_datetime, roll_yearday, shift_month)
 
+import pandas.compat as compat
 from pandas._libs.tslibs import (
     NaT, OutOfBoundsDatetime, Timedelta, Timestamp, ccalendar, conversion,
     delta_to_nanoseconds, frequencies as libfrequencies, normalize_date,
     offsets as liboffsets, timezones)
-from pandas._libs.tslibs.offsets import (
-    ApplyTypeError, BaseOffset, _get_calendar, _is_normalized, _to_dt64,
-    apply_index_wraps, as_datetime, roll_yearday, shift_month)
-import pandas.compat as compat
 from pandas.compat import range
-from pandas.errors import AbstractMethodError
-from pandas.util._decorators import cache_readonly
-
 from pandas.core.dtypes.generic import ABCPeriod
-
 from pandas.core.tools.datetimes import to_datetime
+from pandas.errors import AbstractMethodError
+from pandas.util._decorators import cache_readonly, Substitution, Appender
 
 __all__ = ['Day', 'BusinessDay', 'BDay', 'CustomBusinessDay', 'CDay',
            'CBMonthEnd', 'CBMonthBegin',
@@ -973,7 +971,7 @@ class BusinessMonthBegin(MonthOffset):
 class _CustomBusinessMonth(_CustomMixin, BusinessMixin, MonthOffset):
     """
     DateOffset subclass representing one custom business month, incrementing
-    between [BEGIN/END] of month dates.
+    between %(bound)s of month dates.
 
     Parameters
     ----------
@@ -1053,18 +1051,15 @@ def apply(self, other):
         return result
 
 
+@Substitution(bound="end")
+@Appender(_CustomBusinessMonth.__doc__)
 class CustomBusinessMonthEnd(_CustomBusinessMonth):
-    # TODO(py27): Replace condition with Subsitution after dropping Py27
-    if _CustomBusinessMonth.__doc__:
-        __doc__ = _CustomBusinessMonth.__doc__.replace('[BEGIN/END]', 'end')
     _prefix = 'CBM'
 
 
+@Substitution(bound="beginning")
+@Appender(_CustomBusinessMonth.__doc__)
 class CustomBusinessMonthBegin(_CustomBusinessMonth):
-    # TODO(py27): Replace condition with Subsitution after dropping Py27
-    if _CustomBusinessMonth.__doc__:
-        __doc__ = _CustomBusinessMonth.__doc__.replace('[BEGIN/END]',
-                                                       'beginning')
     _prefix = 'CBMS'