Err<T, E> class final

Result is a type that that represents either success (Ok) or failure (Err)

Examples

Basic usage:

class FallibleOpSuccess {}
class FallibleOpFailure {}

Result<FallibleOpSuccess, FallibleOpFailure> fallibleOp() {
  if (true) {
    return Ok(FallibleOpSuccess());
  } else {
    return Err(FallibleOpFailure());
  }
}

final result = fallibleOp();

result.inspect((value) {
    print('Success with value: $value');
  }).inspectErr((error) {
    print('Failure with error: $error');
  });
}

Inheritance

• Object
• Result<T, E>
• Err

Constructors

Err(E e)

Result is a type that that represents either success (Ok) or failure (Err)

const

Properties

e → E

Err wrapped error

final

hashCode → int

The hash code for this object.

no setter, override

isErr → bool

Resturns true if the result is Err (failure)

no setter, override

isOk → bool

Resturns true if the result is Ok (success)

no setter, override

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

and<U>(Result<U, E> res) → Result<U, E>

Return res if the result is Ok, otherwise returns the Err value of this.

override

andThen<U>(Result<U, E> okMap(T value)) → Result<U, E>

Calls op if the result is Ok, otherwise returns the Err value of this.

override

contains(Object? x) → bool

Returns true if the result is an Ok (success) value containing the given value.

override

containsErr(Object? x) → bool

Returns true if the result is an Err (failure) value containing the given value.

override

err() → E?

Converts from Result<T, E> to E?.

override

expect(String message) → T

Returns the contained Ok (success) value.

override

expectErr(String message) → E

Returns the contained Err (failure) value.

override

inspect(void f(T value)) → Result<T, E>

Calls the provided closure with the contained value (if Ok)

override

inspectErr(void f(E error)) → Result<T, E>

Calls the provided closure with the contained error (if Err).

override

isErrAnd(bool f(E error)) → bool

Returns true if the result is Err and the value matches the predicate f

override

isOkAnd(bool f(T value)) → bool

Returns true if the result is Ok and the value matches the predicate f

override

map<U>(U okMap(T value)) → Result<U, E>

Maps a Result<T, E> to Result<U, E> by applying a function to a contained Ok (success) value, and leaving an Err (failure) value untouched.

override

mapErr<F>(F errMap(E error)) → Result<T, F>

Maps a Result<T, E> to Result<T, F> by applying a function to a contained Err (failure) value, leaving an Ok (success) value untouched.

override

mapOr<U>({required U fallback, required U okMap(T value)}) → U

Returns the provided fallback (if Err (failure)), or applies a function to the contained value (if Ok (success)).

override

mapOrElse<U>({required U errMap(E error), required U okMap(T value)}) → U

Maps a Result<T, E> to U by applying fallback function fallback to a contained Err (failure) value, or function op to a contained Ok (success) value.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

ok() → T?

Converts from Result<T, E> to T?.

override

or<F>(Result<T, F> res) → Result<T, F>

Returns res if the result is Err, otherwise returns the Ok (success) value of this.

override

orElse<F>(Result<T, F> errMap(E error)) → Result<T, F>

Calls op if the result is Err, otherwise returns the Ok value of this.

override

toString() → String

A string representation of this object.

override

unwrap() → T

Returns the contained Ok (success) value. Because this function may throw an exception, its use is generally discouraged. Instead, prefer to use switch statements with the Result.type and handle the Err (failure) case explicitly, or call `unwrapOr`, `unwrapOrElse`.

override

unwrapErr() → E

Returns the contained Err (failure) value.

override

unwrapOr(T fallback) → T

Returns the contained Ok (success) value or a provided fallback.

override

unwrapOrElse(T fallback(E error)) → T

Returns the contained Ok (success) value or computes it from the closure.

override

when<U>({required U ok(T value), required U err(E error)}) → U

Maps a Result<T, E> to U

override

Operators

operator ==(Object? other) → bool

The equality operator.

override