発展させてみた #CodePiece

CodePiece.swift

struct GeneratedError<T>: Error {
    
    let host: T
    let id: Int
    let message: String
    
    let file: String
    let line: Int
    
    init(_ host: T, id: Int = 0, message: String = "", file: String, line: Int) {
        self.host = host
        self.id = id
        self.message = message
        
        self.file = file
        self.line = line
    }
}
extension GeneratedError: CustomStringConvertible {
    
    var description: String {
        """
GeneratedError {
    host:    \(host),
    id:      \(id),
    message: "\(message)"
    positiion: \(file)#\(line)
}
"""
    }
}
protocol ErrorGenaratable {}
extension ErrorGenaratable {
    
    func generateError(_ id: Int, _ message: String, file: String = #file, line: Int = #line) -> GeneratedError<Self> {
        .init(self, id: id, message: message, file: file, line: line)
    }
    func generateError(_ id: Int, file: String = #file, line: Int = #line) -> GeneratedError<Self> {
        .init(self, id: id, file: file, line: line)
    }
    func generateError(file: String = #file, line: Int = #line) -> GeneratedError<Self> {
        .init(self, file: file, line: line)
    }
}

struct Hoge: ErrorGenaratable {
    
    func hoge() throws {
        throw generateError()
    }
}
struct Fuga: ErrorGenaratable {
    
    func fuga0() throws {
        throw generateError(0)
    }
    func fuga1() throws {
        throw generateError(1)
    }
}

do {
    try Fuga().fuga0()
    try Hoge().hoge()
    try Fuga().fuga1()
}
catch let error as GeneratedError<Hoge> {
    print(error)
}
catch let error as GeneratedError<Fuga> {
    switch error.id {
    case 0: print("Fuga id 0\n", error)
    case 1: print("Fuga id 1\n", error)
    default: print("Unknown\n", error)
    }
}