Add new overload for AddTypeReader (#1009)

src/Discord.Net.Commands/Builders/ModuleClassBuilder.cs

@@ -291,7 +291,7 @@ namespace Discord.Commands
 
             //We dont have a cached type reader, create one
             reader = ReflectionUtils.CreateObject<TypeReader>(typeReaderType.GetTypeInfo(), service, services);
-            service.AddTypeReader(paramType, reader);
+            service.AddTypeReader(paramType, reader, false);
 
             return reader;
         }

src/Discord.Net.Commands/CommandService.cs

@@ -215,10 +215,11 @@ namespace Discord.Commands
             return true;
         }
 
-        //Type Readers 
+        //Type Readers
         /// <summary>
         /// Adds a custom <see cref="TypeReader"/> to this <see cref="CommandService"/> for the supplied object type. 
         /// If <typeparamref name="T"/> is a <see cref="ValueType"/>, a <see cref="NullableTypeReader{T}"/> will also be added.
+        /// If a default <see cref="TypeReader"/> exists for <typeparamref name="T"/>, a warning will be logged and the default <see cref="TypeReader"/> will be replaced. 
         /// </summary>
         /// <typeparam name="T">The object type to be read by the <see cref="TypeReader"/>.</typeparam>
         /// <param name="reader">An instance of the <see cref="TypeReader"/> to be added.</param>
@@ -226,17 +227,53 @@ namespace Discord.Commands
             => AddTypeReader(typeof(T), reader);
         /// <summary>
         /// Adds a custom <see cref="TypeReader"/> to this <see cref="CommandService"/> for the supplied object type. 
-        /// If <paramref name="type"/> is a <see cref="ValueType"/>, a <see cref="NullableTypeReader{T}"/> for the value type will also be added. 
+        /// If <paramref name="type"/> is a <see cref="ValueType"/>, a <see cref="NullableTypeReader{T}"/> for the value type will also be added.
+        /// If a default <see cref="TypeReader"/> exists for <paramref name="type"/>, a warning will be logged and the default <see cref="TypeReader"/> will be replaced.
         /// </summary>
         /// <param name="type">A <see cref="Type"/> instance for the type to be read.</param>
         /// <param name="reader">An instance of the <see cref="TypeReader"/> to be added.</param>
         public void AddTypeReader(Type type, TypeReader reader)
         {
-            var readers = _typeReaders.GetOrAdd(type, x => new ConcurrentDictionary<Type, TypeReader>());
+            if (_defaultTypeReaders.ContainsKey(type))
-            readers[reader.GetType()] = reader;
+                _cmdLogger.WarningAsync($"The default TypeReader for {type.FullName} was replaced by {reader.GetType().FullName}. To suppress this message, use the overload that has a Boolean to replace the default one and pass true.").GetAwaiter().GetResult();
+            AddTypeReader(type, reader, true);
+        }
+        /// <summary>
+        /// Adds a custom <see cref="TypeReader"/> to this <see cref="CommandService"/> for the supplied object type. 
+        /// If <typeparamref name="T"/> is a <see cref="ValueType"/>, a <see cref="NullableTypeReader{T}"/> will also be added.
+        /// </summary>
+        /// <typeparam name="T">The object type to be read by the <see cref="TypeReader"/>.</typeparam>
+        /// <param name="reader">An instance of the <see cref="TypeReader"/> to be added.</param>
+        /// <param name="replaceDefaultTypeReader">If <paramref name="reader"/> should replace the default <see cref="TypeReader"/> for <typeparamref name="T"/> if one exists.</param>
+        public void AddTypeReader<T>(TypeReader reader, bool replaceDefaultTypeReader)
+            => AddTypeReader(typeof(T), reader, replaceDefaultTypeReader);
+        /// <summary>
+        /// Adds a custom <see cref="TypeReader"/> to this <see cref="CommandService"/> for the supplied object type. 
+        /// If <paramref name="type"/> is a <see cref="ValueType"/>, a <see cref="NullableTypeReader{T}"/> for the value type will also be added. 
+        /// </summary>
+        /// <param name="type">A <see cref="Type"/> instance for the type to be read.</param>
+        /// <param name="reader">An instance of the <see cref="TypeReader"/> to be added.</param>
+        /// <param name="replaceDefaultTypeReader">If <paramref name="reader"/> should replace the default <see cref="TypeReader"/> for <paramref name="type"/> if one exists.</param>
+        public void AddTypeReader(Type type, TypeReader reader, bool replaceDefaultTypeReader)
+        {
+            if (replaceDefaultTypeReader && _defaultTypeReaders.ContainsKey(type))
+            {
+                _defaultTypeReaders.AddOrUpdate(type, reader, (k, v) => reader);
+                if (type.GetTypeInfo().IsValueType)
+                {
+                    var nullableType = typeof(Nullable<>).MakeGenericType(type);
+                    var nullableReader = NullableTypeReader.Create(type, reader);
+                    _defaultTypeReaders.AddOrUpdate(nullableType, nullableReader, (k, v) => nullableReader);
+                }
+            }
+            else
+            {
+                var readers = _typeReaders.GetOrAdd(type, x => new ConcurrentDictionary<Type, TypeReader>());
+                readers[reader.GetType()] = reader;
 
-            if (type.GetTypeInfo().IsValueType)
+                if (type.GetTypeInfo().IsValueType)
-                AddNullableTypeReader(type, reader);
+                    AddNullableTypeReader(type, reader);
+            }
         }
         internal void AddNullableTypeReader(Type valueType, TypeReader valueTypeReader)
         {