check that hash and equality works in DecoratedPermutation, restore h…

…ash in OrderedMultisetPartitionIntoSets and AbstractSetPartition

src/sage/combinat/decorated_permutation.py

@@ -53,6 +53,26 @@ def __classcall_private__(cls, pi):
             sage: DecoratedPermutation([2, 1, -3])
             [2, 1, -3]
 
+        TESTS:
+
+        Check that hashing and comparison works::
+
+            sage: S = DecoratedPermutations(3)
+            sage: elt1 = S([2, 1, -3])
+            sage: elt2 = DecoratedPermutation([2, 1, -3])
+            sage: elt1 == elt2
+            True
+
+            sage: elt1 == [2, 1, -3]
+            False
+
+            sage: elt2 = DecoratedPermutation([2, 1, 3])
+            sage: elt1 != elt2
+            True
+
+            sage: hash(elt1)                                                    # random
+            915443076393556996
+
         """
         pi = list(pi)
         return DecoratedPermutations(len(pi))(pi)
@@ -86,46 +106,6 @@ def check(self):
         if self not in self.parent():
             raise ValueError("{} is not a decorated permutation".format(self))
 
-    def __eq__(self, other):
-        """
-        Check whether ``self`` is equal to ``other``.
-
-        INPUT:
-
-        - ``other`` -- the element that ``self`` is compared to
-
-        OUTPUT: Boolean
-
-        EXAMPLES::
-
-            sage: S = DecoratedPermutations(3)
-            sage: elt1 = S([2, 1, -3])
-            sage: elt2 = DecoratedPermutation([2, 1, -3])
-            sage: elt1 == elt2
-            True
-        """
-        return isinstance(other, DecoratedPermutation) and list(self) == list(other)
-
-    def __ne__(self, other):
-        """
-        Check whether ``self`` is not equal to ``other``.
-
-        INPUT:
-
-        - ``other`` -- the element that ``self`` is compared to
-
-        OUTPUT: Boolean
-
-        EXAMPLES::
-
-            sage: S = DecoratedPermutations(3)
-            sage: elt1 = S([2, 1, -3])
-            sage: elt2 = DecoratedPermutation([2, 1, 3])
-            sage: elt1 != elt2
-            True
-        """
-        return not (self == other)
-
     def size(self):
         """
         Return the size of the decorated permutation.

src/sage/combinat/multiset_partition_into_sets_ordered.py

@@ -273,6 +273,22 @@ def _repr_tight(self):
         # eliminate spacing within blocks
         return repr.replace(", ", ",").replace("},{", "}, {")
 
+    def __hash__(self):
+        """
+        Return the hash of ``self``.
+
+        The parent is not included as part of the hash.
+
+        EXAMPLES::
+
+            sage: OMP = OrderedMultisetPartitionsIntoSets(4)
+            sage: A = OMP([[1], [1, 2]])
+            sage: B = OMP([{1}, {1, 2}])
+            sage: hash(A) == hash(B)
+            True
+        """
+        return sum(hash(x) for x in self)
+
     def __eq__(self, y):
         """
         Check equality of ``self`` and ``y``.

src/sage/combinat/set_partition.py

@@ -73,6 +73,22 @@ def _repr_(self):
         """
         return '{' + ', '.join(('{' + repr(sorted(x))[1:-1] + '}' for x in self)) + '}'
 
+    def __hash__(self):
+        """
+        Return the hash of ``self``.
+
+        The parent is not included as part of the hash.
+
+        EXAMPLES::
+
+            sage: P = SetPartitions(4)
+            sage: A = SetPartition([[1], [2,3], [4]])
+            sage: B = P([[1], [2,3], [4]])
+            sage: hash(A) == hash(B)
+            True
+        """
+        return sum(hash(x) for x in self)
+
     def __eq__(self, y):
         """
         Check equality of ``self`` and ``y``.