skyreach_result 1.0.2

Provide a common and easy-to-use Result type

This package provides a Result type under which success (Ok) and failure (Err) are represented. The Result type is a type of Union(Either) that is specialized for error handling and has useful methods for error handling.

Usage

Creating a Result object

Result<int, String>.ok(42);
Result<int, String>.err("Error");

Ok or Err judgment

final result = Result<int, String>.ok(42);

result.isOk; // true
result.isErr; // false

Getting the value of Result

final result = Result<int, String>.ok(42);
// ok, err raises assertion error if value cannot be returned
result.ok; // 42
result.err; // AssertionError

// okOrNull, errOrNull returns null if no value can be returned
result.okOrNull; // 42
result.errOrNull; // null

// okOr, errOr returns the default value taken as argument if no value can be returned
result.okOr(100); // 42
result.errOr("hello"); // "hello"

Using and Converting Result Values

final result = Result<int, String>.ok(42);
// If the Result type is ok, the first argument is executed, if the Result type is err, the second argument is executed
result.when(
  (ok) => ok , // 42
  (_) => expect(true, false), // not called
);

result.map<double>(
  (ok) => ok.toDouble(),
  (err) => 0.0
); // 42.0