1/* 2 * Copyright (c) 2021-2025 Huawei Device Co., Ltd. 3 * Licensed under the Apache License, Version 2.0 (the "License"); 4 * you may not use this file except in compliance with the License. 5 * You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software 10 * distributed under the License is distributed on an "AS IS" BASIS, 11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 * See the License for the specific language governing permissions and 13 * limitations under the License. 14 */ 15 16/*--- 17desc: 9.6.10 Overriding by Instance Methods 18name: 09.classes/09.06.method_declarations/09.06.10.overriding_by_instance_methods/override_optional_param_01 19tags: [] 20---*/ 21 22class A<T> { 23 returnHello(op?: T): string { 24 const extra: string = op ? op?.toString() : "" 25 return "hello A " + extra; 26 } 27} 28 29class B<T> extends A<T> { 30 returnHello(op?: T): string { 31 const extra: string = op ? op?.toString() : "" 32 return "hello B " + extra; 33 } 34} 35 36function main(): void { 37 let b: A<string> = new B<string>() 38 assertEQ( b.returnHello(), "hello B ") 39} 40