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| import Foundation | |
| public protocol ComputedPropertyProvider { | |
| var computedProperty:String { get} | |
| } | |
| public extension ComputedPropertyProvider { | |
| var computedProperty: String { | |
| return "this is computed property" | |
| } | |
| } | |
| public protocol FuncProvider { | |
| func someFunc() | |
| } | |
| public extension FuncProvider { | |
| func someFunc() { | |
| print("someFunc") | |
| } | |
| } | |
| //SomeType does not provide its own implementations of the property and func on these protocols, relying | |
| //on the implementations provided via the protocol extensions. | |
| public class SomeType: ComputedPropertyProvider, FuncProvider { | |
| func usefulStuffNotOnAProtocol() { | |
| print("imagine useful functionality here") | |
| } | |
| } | |
| //AnotherType uses protcol extensions to conform to ComputedPropertyProvider and FuncProvider | |
| //but also provides its own implementations of the property and func. | |
| public class AnotherType {} | |
| extension AnotherType: ComputedPropertyProvider { | |
| public var computedProperty: String { | |
| return "computedProperty from AnotherType" | |
| } | |
| } | |
| extension AnotherType: FuncProvider { | |
| public func someFunc() { | |
| print("someFunc from AnotherType") | |
| } | |
| } | |
| //This will not compile just fine without the following constraints after T: SomeType: | |
| //where T: ComputedPropertyProvider, T: FuncProvider. Go ahead and remove those and watch it fail. | |
| //Doesn't seem like it should be needed because Swift knows at compile time that SomeType conforms | |
| //to the appropriate protocols. | |
| func doSomething<T: SomeType where T: ComputedPropertyProvider, T: FuncProvider>(parameter: T) { | |
| print("computedProperty is \(parameter.computedProperty)") | |
| parameter.someFunc() | |
| parameter.usefulStuffNotOnAProtocol() | |
| } | |
| //This func doesn't need the where constraints to compile because AnotherType declares its own property and func | |
| //even though they are declared in an extension along with AnotherType's conformance to the same | |
| //two protocols. | |
| func doSomethingElse<T: AnotherType>(parameter: T) { | |
| print("computedProperty is \(parameter.computedProperty)") | |
| parameter.someFunc() | |
| } | |
| let someType = SomeType() | |
| doSomething(someType) | |
| let anotherType = AnotherType() | |
| doSomethingElse(anotherType) | |
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