add support for weakly typed arrays, aka object array.

Dapper/SqlMapper.cs

@@ -286,41 +286,34 @@ public bool Equals(Identity other)
         {
             IEnumerable multiExec = (object)param as IEnumerable;
             Identity identity;
-            CacheInfo info;
+            CacheInfo info = null;
             if (multiExec != null && !(multiExec is string))
-            { // we actually want a T from IEnumerable<T>
-                var interfaces = multiExec.GetType().GetInterfaces();
-                var openType = typeof(IEnumerable<>);
-                Type foundType = null;
-                for (int i = 0; i < interfaces.Length; i++)
-                {
-                    if (interfaces[i].IsGenericType && interfaces[i].GetGenericTypeDefinition() == openType)
-                    { // implementing more than one T is self-inflicted
-                        foundType = interfaces[i].GetGenericArguments()[0];
-                        identity = new Identity(sql, cnn, null, foundType, null);
-                        info = GetCacheInfo(identity);
-                        using (var cmd = SetupCommand(cnn, transaction, sql, null, null, commandTimeout, commandType))
             { 
                 bool isFirst = true;
-                            var masterSql = cmd.CommandText;
-                            var reader = info.ParamReader;
                 int total = 0;
+                using (var cmd = SetupCommand(cnn, transaction, sql, null, null, commandTimeout, commandType))
+                {
+                    
+                    string masterSql = null; 
                     foreach (var obj in multiExec)
                     {
-                                if (isFirst) { isFirst = false; }
+                        if (isFirst)
+                        {
+                            masterSql = cmd.CommandText;
+                            isFirst = false;
+                            identity = new Identity(sql, cnn, null, obj.GetType(), null);
+                            info = GetCacheInfo(identity);
+                        }
                         else
                         {
                             cmd.CommandText = masterSql; // because we do magic replaces on "in" etc
                             cmd.Parameters.Clear(); // current code is Add-tastic
                         }
-                                reader(cmd, obj);
+                        info.ParamReader(cmd, obj);
                         total += cmd.ExecuteNonQuery();
                     }
-                            return total;
-                        }
                 }
-                }
-
+                return total;
             }
 
             // nice and simple

Tests/Tests.cs

@@ -226,6 +226,15 @@ public void TestExecuteMultipleCommand()
             sum.IsEqualTo(10);
         }
 
+        public void TestExecuteMultipleCommandObjectArray()
+        {
+            connection.Execute("create table #t(i int)");
+            int tally = connection.Execute(@"insert #t (i) values(@a)", new object[] { new { a = 1 }, new { a = 2 }, new { a = 3 }, new { a = 4 } });
+            int sum = connection.Query<int>("select sum(i) from #t drop table #t").First();
+            tally.IsEqualTo(4);
+            sum.IsEqualTo(10);
+        }
+
         public void TestMassiveStrings()
         {
             var str = new string('X', 20000);