Tslibs offsets immutable

pandas/_libs/tslibs/offsets.pyx

@@ -10,6 +10,7 @@ from dateutil.relativedelta import relativedelta
 
 import numpy as np
 cimport numpy as np
+from numpy cimport int64_t
 np.import_array()
 
 
@@ -315,8 +316,8 @@ class EndMixin(object):
 
 # ---------------------------------------------------------------------
 # Base Classes
-
-class _BaseOffset(object):
+@cython.auto_pickle(False)
+cdef class _BaseOffset(object):
     """
     Base class for DateOffset methods that are not overriden by subclasses
     and will (after pickle errors are resolved) go into a cdef class.
@@ -325,6 +326,14 @@ class _BaseOffset(object):
     _normalize_cache = True
     _cacheable = False
 
+    cdef readonly:
+        int64_t n
+        bint normalize
+
+    def __init__(self, n=1, normalize=False):
+        self.n = n
+        self.normalize = normalize
+
     def __call__(self, other):
         return self.apply(other)
 
@@ -361,6 +370,58 @@ class _BaseOffset(object):
         out = '<%s' % n_str + className + plural + self._repr_attrs() + '>'
         return out
 
+    def __setstate__(self, state):
+        """Reconstruct an instance from a pickled state"""
+        # Note: __setstate__ needs to be defined in the cython class otherwise
+        # trying to set self.n and self.normalize below will
+        # raise an AttributeError.
+        if 'normalize' not in state:
+            # default for prior pickles
+            # See GH #7748, #7789
+            state['normalize'] = False
+        if '_use_relativedelta' not in state:
+            state['_use_relativedelta'] = False
+
+        if 'offset' in state:
+            # Older versions Business offsets have offset attribute
+            # instead of _offset
+            if '_offset' in state:  # pragma: no cover
+                raise ValueError('Unexpected key `_offset`')
+            state['_offset'] = state.pop('offset')
+            state['kwds']['offset'] = state['_offset']
+
+        self.n = state.pop('n', 1)
+        self.normalize = state.pop('normalize', False)
+        self.__dict__ = state
+
+        if 'weekmask' in state and 'holidays' in state:
+            # Business subclasses
+            calendar, holidays = _get_calendar(weekmask=self.weekmask,
+                                               holidays=self.holidays,
+                                               calendar=None)
+            self.kwds['calendar'] = self.calendar = calendar
+            self.kwds['holidays'] = self.holidays = holidays
+            self.kwds['weekmask'] = state['weekmask']
+
+    def __getstate__(self):
+        """Return a pickleable state"""
+        state = self.__dict__.copy()
+
+        # Add attributes from the C base class that aren't in self.__dict__
+        state['n'] = self.n
+        state['normalize'] = self.normalize
+
+        # we don't want to actually pickle the calendar object
+        # as its a np.busyday; we recreate on deserilization
+        if 'calendar' in state:
+            del state['calendar']
+        try:
+            state['kwds'].pop('calendar')
+        except KeyError:
+            pass
+
+        return state
+
 
 class BaseOffset(_BaseOffset):
     # Here we add __rfoo__ methods that don't play well with cdef classes

pandas/compat/pickle_compat.py

@@ -2,6 +2,7 @@
 Support pre-0.12 series pickle compatibility.
 """
 
+import inspect
 import sys
 import pandas  # noqa
 import copy
@@ -22,7 +23,6 @@ def load_reduce(self):
         stack[-1] = func(*args)
         return
     except Exception as e:
-
         # If we have a deprecated function,
         # try to replace and try again.
 
@@ -47,6 +47,22 @@ def load_reduce(self):
             except:
                 pass
 
+        if (len(args) and inspect.isclass(args[0]) and
+                getattr(args[0], '_typ', None) == 'dateoffset' and
+                args[1] is object):
+            # See GH#17313
+            from pandas.tseries import offsets
+            args = (args[0], offsets.BaseOffset,) + args[2:]
+            if len(args) == 3 and args[2] is None:
+                args = args[:2] + (1,)
+                # kludge
+            try:
+                stack[-1] = func(*args)
+                return
+            except:
+                pass
+
+
         # unknown exception, re-raise
         if getattr(self, 'is_verbose', None):
             print(sys.exc_info())

pandas/tests/tseries/test_offsets.py

@@ -539,8 +539,7 @@ def setup_method(self, method):
     def test_different_normalize_equals(self):
         # equivalent in this special case
         offset = BDay()
-        offset2 = BDay()
-        offset2.normalize = True
+        offset2 = BDay(normalize=True)
         assert offset == offset2
 
     def test_repr(self):
@@ -734,8 +733,7 @@ def test_constructor_errors(self):
     def test_different_normalize_equals(self):
         # equivalent in this special case
         offset = self._offset()
-        offset2 = self._offset()
-        offset2.normalize = True
+        offset2 = self._offset(normalize=True)
         assert offset == offset2
 
     def test_repr(self):
@@ -1426,8 +1424,7 @@ def test_constructor_errors(self):
     def test_different_normalize_equals(self):
         # equivalent in this special case
         offset = self._offset()
-        offset2 = self._offset()
-        offset2.normalize = True
+        offset2 = self._offset(normalize=True)
         assert offset == offset2
 
     def test_repr(self):
@@ -1667,8 +1664,7 @@ def setup_method(self, method):
     def test_different_normalize_equals(self):
         # equivalent in this special case
         offset = CDay()
-        offset2 = CDay()
-        offset2.normalize = True
+        offset2 = CDay(normalize=True)
         assert offset == offset2
 
     def test_repr(self):
@@ -1953,8 +1949,7 @@ class TestCustomBusinessMonthEnd(CustomBusinessMonthBase, Base):
     def test_different_normalize_equals(self):
         # equivalent in this special case
         offset = CBMonthEnd()
-        offset2 = CBMonthEnd()
-        offset2.normalize = True
+        offset2 = CBMonthEnd(normalize=True)
         assert offset == offset2
 
     def test_repr(self):
@@ -2067,8 +2062,7 @@ class TestCustomBusinessMonthBegin(CustomBusinessMonthBase, Base):
     def test_different_normalize_equals(self):
         # equivalent in this special case
         offset = CBMonthBegin()
-        offset2 = CBMonthBegin()
-        offset2.normalize = True
+        offset2 = CBMonthBegin(normalize=True)
         assert offset == offset2
 
     def test_repr(self):
@@ -4899,3 +4893,15 @@ def test_all_offset_classes(self):
             first = Timestamp(test_values[0], tz='US/Eastern') + offset()
             second = Timestamp(test_values[1], tz='US/Eastern')
             assert first == second
+
+
+def test_date_offset_immutable():
+    offset = offsets.MonthBegin(n=2, normalize=True)
+    with pytest.raises(AttributeError):
+        offset.n = 1
+
+    # Check that it didn't get changed
+    assert offset.n == 2
+
+    with pytest.raises(AttributeError):
+        offset.normalize = False