Err<T, E> class final

A type that represents an unsuccessful Result.

Pattern matching is recommended for interacting with Result types, for example:

final Result<int, String> foo = Err('Some err');
if (foo case Err(e: final err)) {
  print('Error value: $err');
}
Inheritance
Available extensions

Constructors

Err(E e)
const

Properties

e → E
final
hashCode → int
The hash code for this object.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

and<U>(Result<U, E> other) → Result<U, E>
If this is Ok, it returns other; else if this is Err, it repackages the contained error from Err<T,E> to Err<U, E>.
inherited
andThen<U>(Result<U, E> fn(T okV)) → Result<U, E>
If this is Ok, it returns fn(v), where v is the contained value; else if this is Err, it repackages the contained error from Err<T,E> to Err<U, E>.
inherited
err() → Option<E>
Converts this into an Option<E>, discarding the held T value if this is Ok.
inherited
expect(String message) → T
Returns the contained Ok value.
inherited
expectErr(String message) → E
Returns the contained Err value.
inherited
inspect(void fn(T okV)) → Result<T, E>
If this is Ok, it calls the provided function fn with the contained value.
inherited
inspectErr(void fn(E errE)) → Result<T, E>
If this is Err, it calls the provided function fn with the contained error.
inherited
isErr() → bool
Returns true if this is Err.
inherited
isErrAnd(bool predicate(E errE)) → bool
Returns true if this is Err and the value inside of it matches predicate.
inherited
isOk() → bool
Returns true if this is Ok.
inherited
isOkAnd(bool predicate(T okV)) → bool
Returns true if this is Ok and the value inside of it matches a predicate.
inherited
iter() → Iterable<T>
Returns an Iterable of the possibly contained value.
inherited
map<U>(U mapFn(T okV)) → Result<U, E>
If this is Ok, it applies the provided function to the contained value and packages the newly computed value with Ok<U,E>; else if this is Err, it repackages the contained error from Err<T, E> to Err<U, E>.
inherited
mapErr<F>(F mapFn(E errE)) → Result<T, F>
If this is Err, it applies the provided function to the contained error and packages the newly computed error with Err<T, F>; else if this is Ok, it repackages the contained value (from Ok<T, E> to Ok<T, F>).
inherited
mapOr<U>(U orValue, U mapFn(T okV)) → U
If this is Ok, it applies the provided function to the contained value and returns the newly computed value; else if this is Err, it returns orValue.
inherited
mapOrElse<U>(U orElse(), U mapFn(T okV)) → U
If this is Ok, it applies the provided function to the contained value and returns the newly computed value; else if this is Err, it returns the computed value of orElse.
inherited
match<U>({required U err(E e), required U ok(T v)}) → U
Alternative to doing pattern matching with switch expressions. Makes pattern matching simpler to invoke, given match being a class member; however, Result and Option pattern matching snippets (VSCode) can be leveraged to make working with built-in pattern matching (switch and case) a breeze.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
ok() → Option<T>
Converts this into an Option<T>, discarding the held E value if this is Err.
inherited
or<F>(Result<T, F> other) → Result<T, F>
If this is Ok, it repackages the contained value from Ok<T,E> to Ok<T, F>; else if this is Err, it returns other.
inherited
orElse<F>(Result<T, F> fn(E errE)) → Result<T, F>
If this is Ok, it repackages the contained value from Ok<T,E> to Ok<T, F>; else if this is Err, it returns fn(e), where e is the contained error.
inherited
sameContent(Result<Object, Object> other) → bool
Compares equality between two Results' contained values.
inherited
toJson(Map<String, dynamic> okToJson(T okV), Map<String, dynamic> errToJson(E errE)) → Map<String, dynamic>
Serializes this Result to a map.
inherited
toString() → String
A string representation of this object.
inherited
try_(ErrPropagationToken<E> et) → T
If this is Ok, it unwraps the value; else if this is Err, it propagates the Err.e error by throwing an ErrPropagation.
inherited
unwrap() → T
Returns the contained Ok value.
inherited
unwrapErr() → E
Returns the contained Err value.
inherited
unwrapOr(T orValue) → T
Returns the contained Ok value or a provided value.
inherited
unwrapOrElse(T orElse(E errE)) → T
Returns the contained Ok value or computes it from the orElse closure.
inherited

Operators

operator ==(Object other) → bool
Compares equality between two Result values. The generic types must match. If only the contained value has to be checked, use sameContent instead.
inherited