CLN: standardize string repr to use __repr__

pandas/core/base.py

@@ -34,31 +34,28 @@
 
 class StringMixin:
     """
-    Implements string methods so long as object defines a `__str__` method.
+    Require that an object defines a `__repr__` method.
     """
-    # side note - this could be made into a metaclass if more than one
-    #             object needs
+    # TODO: Remove this class from the code base. It's not needed after
+    #  dropping python2.
 
-    # ----------------------------------------------------------------------
-    # Formatting
-
-    def __str__(self):
+    def __repr__(self):
         """
         Return a string representation for a particular Object
         """
         raise AbstractMethodError(self)
 
-    def __repr__(self):
-        """
-        Return a string representation for a particular object.
-        """
-        return str(self)
-
 
 class PandasObject(DirNamesMixin):
 
     """baseclass for various pandas objects"""
 
+    subclasses = []
+
+    def __init_subclass__(cls, **kwargs):
+        if hasattr(cls, '_cache'):
+            PandasObject.subclasses.append(cls)
+
     @property
     def _constructor(self):
         """class constructor (for this class it's just `__class__`"""

pandas/core/computation/ops.py

@@ -67,7 +67,7 @@ def __init__(self, name, env, side=None, encoding=None):
     def local_name(self):
         return self.name.replace(_LOCAL_TAG, '')
 
-    def __str__(self):
+    def __repr__(self):
         return pprint_thing(self.name)
 
     def __call__(self, *args, **kwargs):
@@ -166,9 +166,7 @@ def _resolve_name(self):
     def name(self):
         return self.value
 
-    def __str__(self):
-        # in python 2 str() of float
-        # can truncate shorter than repr()
+    def __repr__(self):
         return repr(self.name)
 
 
@@ -188,7 +186,7 @@ def __init__(self, op, operands, *args, **kwargs):
     def __iter__(self):
         return iter(self.operands)
 
-    def __str__(self):
+    def __repr__(self):
         """Print a generic n-ary operator and its operands using infix
         notation"""
         # recurse over the operands
@@ -506,7 +504,7 @@ def __call__(self, env):
         operand = self.operand(env)
         return self.func(operand)
 
-    def __str__(self):
+    def __repr__(self):
         return pprint_thing('{0}({1})'.format(self.op, self.operand))
 
     @property
@@ -531,7 +529,7 @@ def __call__(self, env):
         with np.errstate(all='ignore'):
             return self.func.func(*operands)
 
-    def __str__(self):
+    def __repr__(self):
         operands = map(str, self.operands)
         return pprint_thing('{0}({1})'.format(self.op, ','.join(operands)))
 

pandas/core/computation/pytables.py

@@ -11,7 +11,6 @@
 from pandas.core.dtypes.common import is_list_like
 
 import pandas as pd
-from pandas.core.base import StringMixin
 import pandas.core.common as com
 from pandas.core.computation import expr, ops
 from pandas.core.computation.common import _ensure_decoded
@@ -36,8 +35,7 @@ class Term(ops.Term):
 
     def __new__(cls, name, env, side=None, encoding=None):
         klass = Constant if not isinstance(name, str) else cls
-        supr_new = StringMixin.__new__
-        return supr_new(klass)
+        return object.__new__(klass)
 
     def __init__(self, name, env, side=None, encoding=None):
         super().__init__(name, env, side=side, encoding=encoding)
@@ -230,7 +228,7 @@ def convert_values(self):
 
 class FilterBinOp(BinOp):
 
-    def __str__(self):
+    def __repr__(self):
         return pprint_thing("[Filter : [{lhs}] -> [{op}]"
                             .format(lhs=self.filter[0], op=self.filter[1]))
 
@@ -302,7 +300,7 @@ def evaluate(self):
 
 class ConditionBinOp(BinOp):
 
-    def __str__(self):
+    def __repr__(self):
         return pprint_thing("[Condition : [{cond}]]"
                             .format(cond=self.condition))
 
@@ -549,7 +547,7 @@ def __init__(self, where, queryables=None, encoding=None, scope_level=0):
                                         encoding=encoding)
             self.terms = self.parse()
 
-    def __str__(self):
+    def __repr__(self):
         if self.terms is not None:
             return pprint_thing(self.terms)
         return pprint_thing(self.expr)

pandas/core/computation/scope.py

@@ -78,8 +78,7 @@ def _get_pretty_string(obj):
     return sio.getvalue()
 
 
-class Scope(StringMixin):
-
+class Scope:
     """Object to hold scope, with a few bells to deal with some custom syntax
     and contexts added by pandas.
 
@@ -135,13 +134,13 @@ def __init__(self, level, global_dict=None, local_dict=None, resolvers=(),
         self.resolvers = DeepChainMap(*resolvers)
         self.temps = {}
 
-    def __str__(self):
+    def __repr__(self):
         scope_keys = _get_pretty_string(list(self.scope.keys()))
         res_keys = _get_pretty_string(list(self.resolvers.keys()))
-        unicode_str = '{name}(scope={scope_keys}, resolvers={res_keys})'
-        return unicode_str.format(name=type(self).__name__,
-                                  scope_keys=scope_keys,
-                                  res_keys=res_keys)
+        template = '{name}(scope={scope_keys}, resolvers={res_keys})'
+        return template.format(name=type(self).__name__,
+                               scope_keys=scope_keys,
+                               res_keys=res_keys)
 
     @property
     def has_resolvers(self):

pandas/io/pytables.py

@@ -399,7 +399,6 @@ def _is_metadata_of(group, parent_group):
 
 
 class HDFStore(StringMixin):
-
     """
     Dict-like IO interface for storing pandas objects in PyTables
     either Fixed or Table format.
@@ -520,7 +519,7 @@ def __contains__(self, key):
     def __len__(self):
         return len(self.groups())
 
-    def __str__(self):
+    def __repr__(self):
         return '{type}\nFile path: {path}\n'.format(
             type=type(self), path=pprint_thing(self._path))
 
@@ -1519,8 +1518,7 @@ def get_result(self, coordinates=False):
         return results
 
 
-class IndexCol(StringMixin):
-
+class IndexCol:
     """ an index column description class
 
         Parameters
@@ -1587,7 +1585,7 @@ def set_table(self, table):
         self.table = table
         return self
 
-    def __str__(self):
+    def __repr__(self):
         temp = tuple(
             map(pprint_thing,
                     (self.name,
@@ -1881,7 +1879,7 @@ def __init__(self, values=None, kind=None, typ=None,
         self.set_data(data)
         self.set_metadata(metadata)
 
-    def __str__(self):
+    def __repr__(self):
         temp = tuple(
             map(pprint_thing,
                     (self.name,
@@ -2286,8 +2284,7 @@ def get_attr(self):
         pass
 
 
-class Fixed(StringMixin):
-
+class Fixed:
     """ represent an object in my store
         facilitate read/write of various types of objects
         this is an abstract base class
@@ -2336,7 +2333,7 @@ def pandas_type(self):
     def format_type(self):
         return 'fixed'
 
-    def __str__(self):
+    def __repr__(self):
         """ return a pretty representation of myself """
         self.infer_axes()
         s = self.shape
@@ -3077,7 +3074,7 @@ def table_type_short(self):
     def format_type(self):
         return 'table'
 
-    def __str__(self):
+    def __repr__(self):
         """ return a pretty representatgion of myself """
         self.infer_axes()
         dc = ",dc->[{columns}]".format(columns=(','.join(

pandas/io/stata.py

@@ -712,7 +712,7 @@ def generate_value_label(self, byteorder, encoding):
         return bio.read()
 
 
-class StataMissingValue(StringMixin):
+class StataMissingValue:
     """
     An observation's missing value.