Result<T> class sealed

The outcome of an operation that can fail: either an Ok carrying a value, or an Err carrying a Failure.

Returning a Result keeps failures in the type signature instead of in the control flow, so a caller cannot forget that an operation can fail. The type is sealed, so a switch over it is exhaustive:

final result = await repository.getUser();
switch (result) {
  case Ok(:final value):
    print(value.name);
  case Err(:final failure):
    log(failure.message);
}
Implementers

Properties

failureOrNull → Failure?
The failure when this is an Err, or null when it is an Ok.
no setter
hashCode → int
The hash code for this object.
no setterinherited
isErr → bool
Whether this is an Err.
no setter
isOk → bool
Whether this is an Ok.
no setter
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
valueOrNull → T?
The value when this is an Ok, or null when it is an Err.
no setter

Methods

flatMap<R>(Result<R> transform(T value)) → Result<R>
Chains another fallible operation onto an Ok, passing an Err through untouched.
fold<R>({required R onOk(T value), required R onErr(Failure failure)}) → R
Collapses both branches into a single value of type R.
getOrElse(T fallback) → T
The value when this is an Ok, otherwise fallback.
map<R>(R transform(T value)) → Result<R>
Applies transform to the value of an Ok, passing an Err through untouched.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited