Fix Sum.Equals

dharmatech · Nov 4, 2014 · 289c8ac · 289c8ac
1 parent 6d88e40
commit 289c8ac
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/Symbolism/Symbolism.cs b/Symbolism/Symbolism.cs
@@ -1283,7 +1283,11 @@ public override int GetHashCode()
         { return elts.GetHashCode(); }
 
         public override bool Equals(object obj)
-        { return ListUtils.equal(elts, ((Sum)obj).elts); }
+        {
+            if (obj is Sum) return ListUtils.equal(elts, ((Sum)obj).elts);
+
+            return false;
+        }
         //////////////////////////////////////////////////////////////////////
 
         static List<MathObject> MergeSums(List<MathObject> pElts, List<MathObject> qElts)

diff --git a/Tests/Tests.cs b/Tests/Tests.cs
@@ -59,7 +59,7 @@ static void Main(string[] args)
                 var x = new Symbol("x");
                 var y = new Symbol("y");
                 var z = new Symbol("z");
-
+                
                 Func<int, Integer> Int = (n) => new Integer(n);
 
                 AssertIsTrue(x + x == 2 * x);
@@ -187,6 +187,12 @@ static void Main(string[] args)
 
                 // Console.WriteLine((x + x + x + x) / x);
 
+                #region Sum
+
+                Assert((x + y).Equals(x * y) == false, "(x + y).Equals(x * y)");
+
+                #endregion
+
                 #region FreeOf
 
                 var a = new Symbol("a");