simplify method signature

pandas/core/generic.py

@@ -20,12 +20,11 @@
                                  is_datetime64_dtype,
                                  is_timedelta64_dtype,
                                  is_datetime64tz_dtype,
-                                 is_period_arraylike,
                                  is_list_like,
                                  is_dict_like,
                                  is_re_compilable)
 from pandas.types.cast import _maybe_promote, _maybe_upcast_putmask
-from pandas.types.missing import isnull, notnull, is_valid_fill_value
+from pandas.types.missing import isnull, notnull
 from pandas.types.generic import ABCSeries, ABCPanel
 
 from pandas.core.common import (_values_from_object,
@@ -3383,11 +3382,17 @@ def convert_objects(self, convert_dates=True, convert_numeric=False,
 
     @Appender(_shared_docs['fillna'] % _shared_doc_kwargs)
     def fillna(self, value=None, method=None, axis=None, inplace=False,
-               limit=None, downcast=None, errors=None):
+               limit=None, downcast=None, errors='coerce'):
         inplace = validate_bool_kwarg(inplace, 'inplace')
 
-        if not missing.maybe_fill(self, value, errors):
-            return self
+        try:
+            missing.validate_fill_value(self, value)
+        except TypeError:
+            if errors == 'ignore':
+                return
+            elif errors == 'raise':
+                raise
+            # if errors == 'coerce' continue
 
         if isinstance(value, (list, tuple)):
             raise TypeError('"value" parameter must be a scalar or dict, but '

pandas/core/missing.py

@@ -12,8 +12,7 @@
                                  is_float_dtype, is_datetime64_dtype,
                                  is_datetime64tz_dtype, is_integer_dtype,
                                  _ensure_float64, is_scalar,
-                                 needs_i8_conversion, is_integer,
-                                 is_period_arraylike)
+                                 needs_i8_conversion, is_integer)
 from pandas.types.missing import isnull, is_valid_fill_value
 from pandas.types.generic import ABCSeries
 
@@ -625,7 +624,7 @@ def fill_zeros(result, x, y, name, fill):
     return result
 
 
-def maybe_fill(obj, value, errors):
+def validate_fill_value(obj, value):
     """
 
     Fillna error coercion routine.
@@ -659,16 +658,8 @@ def maybe_fill(obj, value, errors):
     fillna error coercion routine, returns whether or not to continue.
     """
     if isinstance(obj, ABCSeries):
-        if errors is None or errors == 'coerce':
-            return True
-        else:
-            if not is_valid_fill_value(value, obj.dtype):
-                if errors == 'raise':
-                    raise TypeError('"value" parameter must be compatible '
-                                    'with the {0} dtype, but you passed a '
-                                    '"{1}"'.format(obj.dtype,
-                                                   type(value).__name__))
-                else:  # errors == 'ignore'; short-circuit
-                    return False
-    else:
-        return True
+        if not is_valid_fill_value(value, obj.dtype):
+            raise TypeError('"value" parameter must be compatible '
+                            'with the {0} dtype, but you passed a '
+                            '"{1}"'.format(obj.dtype,
+                                           type(value).__name__))

pandas/types/missing.py

@@ -405,6 +405,8 @@ def is_valid_fill_value(value, dtype):
     value : scalar
     dtype: string / dtype
     """
+    if isinstance(value, dict):
+        return True
     if not is_scalar(value):
         # maybe always raise?
         # raise TypeError('"value" parameter must be a scalar or dict, but '