BUG: adds validation for boolean keywords in DataFrame.set_index

ENH: Adds util._validators.validate_keywords_as_bool decorator

Author: richardjgowers

pandas/core/frame.py

@@ -85,6 +85,7 @@
 from pandas.util._decorators import (Appender, Substitution,
                                      rewrite_axis_style_signature)
 from pandas.util._validators import (validate_bool_kwarg,
+                                     validate_keywords_as_bool,
                                      validate_axis_style_args)
 
 from pandas.core.indexes.period import PeriodIndex
@@ -3037,6 +3038,7 @@ def shift(self, periods=1, freq=None, axis=0):
         return super(DataFrame, self).shift(periods=periods, freq=freq,
                                             axis=axis)
 
+    @validate_keywords_as_bool('drop', 'append', 'inplace', 'verify_integrity')
     def set_index(self, keys, drop=True, append=False, inplace=False,
                   verify_integrity=False):
         """
@@ -3102,7 +3104,6 @@ def set_index(self, keys, drop=True, append=False, inplace=False,
         -------
         dataframe : DataFrame
         """
-        inplace = validate_bool_kwarg(inplace, 'inplace')
         if not isinstance(keys, list):
             keys = [keys]
 

pandas/tests/frame/test_validate.py

@@ -31,3 +31,11 @@ def test_validate_bool_args(self, dataframe, func, inplace):
 
         with tm.assert_raises_regex(ValueError, msg):
             getattr(dataframe, func)(**kwargs)
+
+    @pytest.mark.parametrize('keyword', ('drop', 'append', 'inplace',
+                                         'verify_integrity'))
+    def test_set_index_validation(self, dataframe, keyword):
+        msg = 'For argument "{}" expected type bool'.format(keyword)
+        kw = {keyword: 'yes please'}
+        with tm.assert_raises_regex(ValueError, msg):
+            dataframe.set_index('b', **kw)

pandas/util/_validators.py

@@ -2,6 +2,7 @@
 Module that contains many useful utilities
 for validating data or function arguments
 """
+import functools
 import warnings
 
 from pandas.core.dtypes.common import is_bool
@@ -320,3 +321,33 @@ def validate_axis_style_args(data, args, kwargs, arg_name, method_name):
         msg = "Cannot specify all of '{}', 'index', 'columns'."
         raise TypeError(msg.format(arg_name))
     return out
+
+
+def validate_keywords_as_bool(*keywords):
+    """For a list of keywords, ensure all are bool
+
+    Usage
+    -----
+    Designed to be used as decorator around methods to check many
+    keywords at once:
+
+    @validate_keywords_as_bool('inplace', 'append')
+    def set_index(self, keys, inplace=False, append=False):
+        etc.
+
+    See Also
+    --------
+    validate_bool_kwargs
+
+    """
+    keywords = set(keywords)
+
+    def validate_kwargs(func):
+        @functools.wraps(func)
+        def validator(*args, **kwargs):
+            # only validate present keywords
+            for kw in keywords.intersection(kwargs.keys()):
+                validate_bool_kwarg(kwargs[kw], kw)
+            return func(*args, **kwargs)
+        return validator
+    return validate_kwargs