如何在Swift中的扩展错误类上具有不同的枚举？

Question

I am trying to make a "base" error, that does all the things I want to do for all my errors, and then extend it for each error to have different ErrorType s. I know that I can't really extend an enum , so I have no idea how I'd be able to accomplish something like this. Below is my current code.

class BaseError: Error {
    enum ErrorType {}

    typealias Context = [String:Any]?;

    private let type: ErrorType
    private let context: Context;
    private let line: Int;
    private let function: String;
    private let file: String;

    init(
        type: ErrorType,
        context: Context,
        line: Int = #line,
        file: String = #file,
        function: String = #function
        ) {
        self.type = type;
        self.context = context;
        self.line = line;
        self.function = function;
        self.file = file;


    }

}

class MyError: BaseError {
    enum ErrorType {
        case noApp
        case noLabel
    }
}

I'd want to do something like throw A11yError(type: .noApp) . Doing that now just tells me Type 'BaseError.ErrorType' has no member 'noApp' .

Answer 1

Have you considered using generics to inject the ErrorType ?

class BaseError<ErrorType>: Error {

    typealias Context = [String:Any]?;

    private let type: ErrorType
    private let context: Context;
    private let line: Int;
    private let function: String;
    private let file: String;

    init(
        type: ErrorType,
        context: Context,
        line: Int = #line,
        file: String = #file,
        function: String = #function
        ) {
        self.type = type;
        self.context = context;
        self.line = line;
        self.function = function;
        self.file = file;


    }

}

enum MyError {
    case noApp
    case noLabel
}


let error = BaseError(type: MyError.noApp, context)