EvaluationMethods should be a new-style class

src/sage/functions/hypergeometric.py

@@ -351,7 +351,7 @@ def _tderivative_(self, a, b, z, *args, **kwargs):
         return (t * derivative(z, diff_param) *
                 hypergeometric([c + 1 for c in a], [c + 1 for c in b], z))
 
-    class EvaluationMethods:
+    class EvaluationMethods(object):
         def _fast_float_(cls, self, *args):
             """
             Do not support the old ``fast_float``.

src/sage/functions/piecewise.py

@@ -283,7 +283,7 @@ def simplify(ex):
         raise NotImplementedError
 
 
-    class EvaluationMethods:
+    class EvaluationMethods(object):
 
         def expression_at(cls, self, parameters, variable, point):
             """

src/sage/symbolic/expression.pyx

@@ -137,6 +137,7 @@ from __future__ import print_function, absolute_import
 
 include "cysignals/signals.pxi"
 
+from inspect import ismethod
 import operator
 from . import ring
 import sage.rings.integer
@@ -11754,7 +11755,7 @@ cdef get_dynamic_class_for_function(unsigned serial):
         ....:     def __init__(self):
         ....:         BuiltinFunction.__init__(self, 'tfunc', nargs=1)
         ....:
-        ....:     class EvaluationMethods:
+        ....:     class EvaluationMethods(object):
         ....:         def argp1(fn, self, x):
         ....:             '''
         ....:             Some documentation about a bogus function.
@@ -11799,7 +11800,7 @@ cdef get_dynamic_class_for_function(unsigned serial):
         ....:     def __init__(self):
         ....:         BuiltinFunction.__init__(self, 'tfunc', nargs=2)
         ....:
-        ....:     class EvaluationMethods:
+        ....:     class EvaluationMethods(object):
         ....:         def argsum(fn, self, x, y):
         ....:             return x + y
         ....:
@@ -11820,13 +11821,12 @@ cdef get_dynamic_class_for_function(unsigned serial):
             from sage.symbolic.function_factory import eval_on_operands
             from sage.structure.misc import getattr_from_other_class
             for name in dir(eval_methods):
-                m = getattr(eval_methods(), name)
-                if callable(m):
+                if ismethod(getattr(eval_methods, name)):
                     new_m = eval_on_operands(getattr_from_other_class(
                         func_class, eval_methods, name))
                     setattr(eval_methods, name, new_m)
             cls = dynamic_class('Expression_with_dynamic_methods',
-                    (Expression,), eval_methods)
+                    (Expression,), eval_methods, prepend_cls_bases=False)
         else:
             cls = Expression