Fix func and add tests

Author: isuruf

symengine/lib/symengine_wrapper.pyx

@@ -782,7 +782,9 @@ class Symbol(Basic):
     def is_Symbol(self):
         return True
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
 
 def symarray(prefix, shape, **kwargs):
@@ -906,7 +908,9 @@ class Rational(Number):
             rat = self.get_num_den()
             return rat[0]._sage_() / rat[1]._sage_()
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
 class Integer(Rational):
 
@@ -1006,7 +1010,9 @@ class Integer(Rational):
     def get_num_den(Basic self):
         return self, 1
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
 
 def dps_to_prec(n):
@@ -1254,7 +1260,9 @@ class Add(Basic):
         deref(X).as_two_terms(symengine.outArg(a), symengine.outArg(b))
         return c2py(a)._sage_() + c2py(b)._sage_()
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
     def as_coefficients_dict(Basic self):
         cdef RCP[const symengine.Add] X = symengine.rcp_static_cast_Add(self.thisptr)
@@ -1295,7 +1303,9 @@ class Mul(Basic):
         deref(X).as_two_terms(symengine.outArg(a), symengine.outArg(b))
         return c2py(a)._sage_() * c2py(b)._sage_()
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
     def as_coefficients_dict(Basic self):
         cdef RCP[const symengine.Mul] X = symengine.rcp_static_cast_Mul(self.thisptr)
@@ -1330,7 +1340,9 @@ class Pow(Basic):
         exp = c2py(deref(X).get_exp())
         return base._sage_() ** exp._sage_()
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
 
 class Function(Basic):
@@ -1559,7 +1571,9 @@ class Abs(OneArgFunction):
         arg = c2py(deref(X).get_arg())._sage_()
         return abs(arg)
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
 class FunctionSymbol(Function):
 
@@ -1711,8 +1725,9 @@ class Max(Function):
         s = self.args_as_sage()
         return sage.max(*s)
 
-    func = __class__
-
+    @property
+    def func(self):
+        return self.__class__
 
 class Min(Function):
 
@@ -1729,7 +1744,9 @@ class Min(Function):
         s = self.args_as_sage()
         return sage.min(*s)
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
 
 class Derivative(Basic):
@@ -1773,7 +1790,9 @@ class Derivative(Basic):
             s.append(c2py(<RCP[const symengine.Basic]>(i))._sage_())
         return arg.diff(*s)
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
 
 class Subs(Basic):
@@ -1822,7 +1841,9 @@ class Subs(Basic):
                 c2py(<RCP[const symengine.Basic]>(P[i]))._sage_()
         return arg.subs(v)
 
-    func = __class__
+    @property
+    def func(self):
+        return self.__class__
 
 
 cdef class MatrixBase:

symengine/tests/test_sympy_compat.py

@@ -67,6 +67,7 @@ def test_Add():
     i = Add(x, y)
     assert isinstance(i, Add)
     assert isinstance(i, Basic)
+    assert i.func(y, x) == i
 
 
 def test_Mul():
@@ -76,6 +77,7 @@ def test_Mul():
     i = Mul(x, y)
     assert isinstance(i, Mul)
     assert isinstance(i, Basic)
+    assert i.func(y, x) == i
 
 
 def test_Pow():
@@ -85,6 +87,7 @@ def test_Pow():
     i = Pow(x, 2)
     assert isinstance(i, Pow)
     assert isinstance(i, Basic)
+    assert i.func(x, 2) == i
 
 
 def test_Max():