multiple_result

Result package for dart inspired by the work of dartz's Either and Kotlin's sealed classes.

This package is perfect to those of you who just want the Multiple results functionality from dartz. 👌

About version 4.0.0 and previous releases

Versions 3.0.0 to 3.2.0 represented the common effort in making this package better. That's why so many breaking changes in just a small time.

Once these updates stopped (because they decided to fork the project) I decided to remove these updates and keep it simple as it was always supposed to be. It's open to suggestions and you should not expect more of these breaking changes any time soon. The package will keep evolving and responding to dart's updates.

Use Result type:

In the return of a function, set it to return a Result type;

Result getSomethingPretty();

then add the Success and the Error types.

Result<String, Exception> getSomethingPretty() {

}

in return of the function, you just need to return

return Success('Something Pretty');

or

return Error(Exception('something ugly happened...'));

The function should look something like this:

Result<String, Exception> getSomethingPretty() {
    if(isOk) {
        return Success('OK!');
    } else {
        return Error(Exception('Not Ok!'));
    }
}

Handling the Result with switch:

void main() {
  final result = getSomethingPretty();
  switch(result) {
    case Success():
      print("${result.success}");
      break;
    case Error():
      print("${result.error}");
      break;
  }
}

Handling the Result with when:

void main() {
    final result = getSomethingPretty();
     final String message = result.when(
        (success) {
          // handle the success here
          return "success";
        },
         (error) {
          // handle the error here
          return "error";
        },
    );

}

Handling the Result with if case:

void main() {
  final result = getSomethingPretty();
  if(result case Success()) {
    // access to .success value
    print("${result.success}");
  }
}

Handling the Result with whenSuccess or whenError

    final result = getSomethingPretty();
    // notice that [whenSuccess] or [whenError] will only be executed if
    // the result is a Success or an Error respectivaly. 
    final output = result.whenSuccess((name) {
        // handle here the success
        return "";
    });
    
    final result = getSomethingPretty();
    
    // [result] is NOT an Error, this [output] will be null.
    final output = result.whenError((exception) {
        // handle here the error
        return "";
    });

Handling the Result with getOrThrow

You may use the getOrThrow to get the value when you're sure that the result was a Success. Be aware that accessing this method when the result is actually an Error will throw a SuccessResultNotFoundException.

    final result = getSomethingPretty();

    if (result.isSuccess()) {
      final mySuccessResult = result.getOrThrow();
    }

Handling the Result with tryGetSuccess

void main() {
    final result = getSomethingPretty();

    String? mySuccessResult;
    if (result.isSuccess()) {
      mySuccessResult = result.tryGetSuccess();
    }
}

Handling the Result with tryGetError

void main() {
    final result = getSomethingPretty();

    Exception? myException;
    if (result.isError()) {
      myException = result.tryGetError();
    }
}

Unit Type

Some results do not need a specific return. Use the Unit type to signal an empty return.

    Result<Unit, Exception>

ResultOf

You may have noticed the ResultOf typedef. It represents a better readability for Result, but as it would be another breaking change, leaving it as an alias would be good enough.