如上所示,任何遵守了ThreeProtocol协议的类型都应该同时实现OneProtocol和TwoProtocol的要求必须实现的方法或属性(引自官方文档,概念比较简单)。 协议的聚合 日常开发中要求一个类型同时遵守多个协议是很常见的,除了使用协议的继承外我们还可以使用形如OneProtocol & TwoProtocol的形式实现协议聚合(组合)复合多个协议到一个...
日常开发中要求一个类型同时遵守多个协议是很常见的,除了使用协议的继承外我们还可以使用形如OneProtocol & TwoProtocol的形式实现协议聚合(组合)复合多个协议到一个要求里。例如: //协议聚合成临时的类型typealias Three = TwoProtocol &OneProtocol//协议聚合成为参数的类型func text(paramter: OneProtocol &TwoProtoco...
Default Implementation of Methods However, the aforementioned technique only really works for operators. Providing a default implementation of a protocol method is less convenient. Consider a protocolPwith a methodm()that takes a singleIntargument: protocolP{funcm(arg:Int)} The closest one can get...
classSomeClass{varname:String?}extensionSomeClass:DescriptionProtocol{}letsomeone=SomeClass()someone.printSomething()//打印出来 "This is a default implementation!" 根据最后的打印结果,我们发现,在我们并未提供实现的情况下,调用了默认的实现。那如果我们又自己提供了方法的实现会使什么样的呢? extensionSomeCla...
protocol OpenProtocol { var debugDescription: String { get } func doSomething() } 1. 2. 3. 4. 协议可能要求: 实例方法是 the actions that the adopting entities must all be able to perform. 本质上是计算属性,disguised getters.因此它们属于actions that all adopting entities must be able to resp...
Extending Protocols With Default Implementations extensionBird{// Flyable birds can fly!varcanFly:Bool{selfisFlyable}}extensionUnladenSwallow{varcanFly:Bool{self!=.unknown}} Extending Protocols protocolBird:CustomStringConvertible{varname:String{get}varcanFly:Bool{get}}extensionCustomStringConvertiblewhereSel...
protocol SomeProtocol { // protocol definition goes here } 自定义类型声明,他们采用特定协议,将协议的名称放在类型名称之后,用冒号分隔,作为其定义的一部分。可以列出多个协议,并用逗号分隔: struct SomeStructure: FirstProtocol, AnotherProtocol { ...
you don't need to do anything beyond/// declaring conformance to the protocol and ensuring that the values of your/// type support negation. To customize your type's implementation, provide/// your own mutating `negate()` method.///因为' SignedNumeric '协议提供了它所需要的两个方法的默认...
classSomeClass: SomeProtocol {requiredinit(someParameter: Int) {//initializer implementation goes here} } required关键字确保了所有实现了协议的类/子类都要显示/隐式的实现构造器。具体参见十三、初始化 Initialization。 如果子类覆盖了父类的Designated构造器,而且需要实现一个协议中的required构造器,那么同时写上ov...
public protocol LanguageModelDataSource { var pathToTrainedData: String { get } }Then pass it to the Tesseract initializer:let customDataSource = CustomDataSource() let tesseract = Tesseract( language: .english, dataSource: customDataSource, engineMode: .lstmOnly )...