CLN/DOC: cache_readonly: remove allow_setting + preserve docstring (#19991)

Author: jorisvandenbossche

pandas/_libs/properties.pyx

@@ -6,31 +6,28 @@ from cpython cimport (
  PyDict_Contains, PyDict_GetItem, PyDict_SetItem)
 
 
-cdef class cache_readonly(object):
+cdef class CachedProperty(object):
 
  cdef readonly:
- object func, name, allow_setting
+ object func, name, __doc__
 
- def __init__(self, func=None, allow_setting=False):
- if func is not None:
- self.func = func
- self.name = func.__name__
- self.allow_setting = allow_setting
-
- def __call__(self, func, doc=None):
+ def __init__(self, func):
  self.func = func
  self.name = func.__name__
- return self
+ self.__doc__ = getattr(func, '__doc__', None)
 
  def __get__(self, obj, typ):
- # Get the cache or set a default one if needed
+ if obj is None:
+ # accessed on the class, not the instance
+ return self
 
+ # Get the cache or set a default one if needed
  cache = getattr(obj, '_cache', None)
  if cache is None:
  try:
  cache = obj._cache = {}
  except (AttributeError):
- return
+ return self
 
  if PyDict_Contains(cache, self.name):
  # not necessary to Py_INCREF
@@ -40,20 +37,9 @@ cdef class cache_readonly(object):
  PyDict_SetItem(cache, self.name, val)
  return val
 
- def __set__(self, obj, value):
-
- if not self.allow_setting:
- raise Exception("cannot set values for [%s]" % self.name)
 
- # Get the cache or set a default one if needed
- cache = getattr(obj, '_cache', None)
- if cache is None:
- try:
- cache = obj._cache = {}
- except (AttributeError):
- return
+cache_readonly = CachedProperty
 
- PyDict_SetItem(cache, self.name, value)
 
 cdef class AxisProperty(object):
  cdef:

pandas/core/indexes/base.py

@@ -1401,7 +1401,7 @@ def _is_strictly_monotonic_decreasing(self):
  def is_lexsorted_for_tuple(self, tup):
  return True
 
- @cache_readonly(allow_setting=True)
+ @cache_readonly
  def is_unique(self):
  """ return if the index has unique values """
  return self._engine.is_unique

pandas/tests/indexes/test_base.py

@@ -519,7 +519,6 @@ def test_is_(self):
  assert not ind.is_(ind.copy())
  assert not ind.is_(ind.copy(deep=False))
  assert not ind.is_(ind[:])
- assert not ind.is_(ind.view(np.ndarray).view(Index))
  assert not ind.is_(np.array(range(10)))
 
  # quasi-implementation dependent

pandas/tests/test_lib.py

@@ -3,6 +3,7 @@
 import pytest
 
 import numpy as np
+from pandas import Index
 from pandas._libs import lib, writers as libwriters
 import pandas.util.testing as tm
 
@@ -198,3 +199,8 @@ def test_get_reverse_indexer(self):
  result = lib.get_reverse_indexer(indexer, 5)
  expected = np.array([4, 2, 3, 6, 7], dtype=np.int64)
  tm.assert_numpy_array_equal(result, expected)
+
+
+def test_cache_readonly_preserve_docstrings():
+ # GH18197
+ assert Index.hasnans.__doc__ is not None