Err<T extends Object?, E extends Object> class final

Represents a failed result containing an error and its stack trace.

This is used when an operation fails. The stackTrace is automatically captured from the current context if not provided.

Example:

Result<int, String> divide(int a, int b) {
  if (b == 0) return Err('Division by zero');
  return Ok(a ~/ b);
}
Inheritance
Available extensions
Annotations
  • @immutable

Constructors

Err(E error, [StackTrace? stackTrace])
Creates an error result with the given error and optional stackTrace.

Properties

err → E?
Returns the error value if this is an Err, otherwise null.
no setterinherited
error → E
The error value that describes why the operation failed.
final
hashCode → int
The hash code for this object.
no setteroverride
isErr → bool
Returns true if this result is a failure (Err).
no setterinherited
isOk → bool
Returns true if this result is a success (Ok).
no setterinherited
ok → T?
Returns the success value if this is an Ok, otherwise null.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
stackTrace → StackTrace
The stack trace at the point where this error was created.
final

Methods

and(Result<T, E> other) → Result<T, E>
Chains operations: returns this result if it's an error, otherwise other.
inherited
andLazy(Result<T, E> otherBlock()) → Result<T, E>
Evaluates otherBlock only when this result is successful.
inherited
andThen<U extends Object?>(Result<U, E> otherBlock(T value)) → Result<U, E>
Transforms the success value into a new result, or propagates the error.
inherited
clone() → Result<T, E>
Returns a shallow copy of this result.
inherited
expect(String message) → T
Unwraps the success value, or throws an exception with message.
inherited
expectErr(String message) → E
Unwraps the error value, or throws an exception with message.
inherited
flatten() → Result<T, E>

Available on Result<Result<T, E>, E>, provided by the FlattenResultExtension extension

Flattens a nested Result into a single Result.
inspectErr(void block(E error)) → Result<T, E>

Available on Result<T, E>, provided by the InspectResultExtension extension

Executes a side effect if this is an error, then returns this unchanged.
inspectOk(void block(T value)) → Result<T, E>

Available on Result<T, E>, provided by the InspectResultExtension extension

Executes a side effect if this is a success, then returns this unchanged.
isErrAnd(bool predicate(E error)) → bool
Checks if this is an error and the error matches the predicate.
inherited
isOkAnd(bool predicate(T value)) → bool
Checks if this is a success and the value matches the predicate.
inherited
map<Y extends Object?>(Y block(T value)) → Result<Y, E>
Transforms the success value using block, leaving errors unchanged.
inherited
mapErr<F extends Object>(F block(E error)) → Result<T, F>
Transforms the error value using block, leaving success values unchanged.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
or(Result<T, E> other) → Result<T, E>
Returns this result if it's a success, otherwise the already-evaluated other.
inherited
orElse<F extends Object>(Result<T, F> otherBlock(E error, StackTrace st)) → Result<T, F>
Returns this success value, or computes a recovery result from the error.
inherited
orLazy(Result<T, E> otherBlock()) → Result<T, E>
Evaluates otherBlock only when this result is an error.
inherited
toOption() → Option<T>
Converts this result into an Option.
inherited
toString() → String
A string representation of this object.
override
unwrap() → T
Returns the success value, or throws the error with its original stack trace.
inherited
unwrapOr(T defaultValue) → T
Returns the success value, or defaultValue if this is an error.
inherited
unwrapOrElse(T block(E error)) → T
Returns the success value, or computes a default from the error.
inherited
unwrapOrNull() → T?
Returns the success value as nullable, or null if this is an error.
inherited

Operators

operator &(Result<T, E> other) → Result<T, E>
Combines two already-evaluated results using the and operator (&).
inherited
operator ==(Object other) → bool
The equality operator.
override
operator |(Result<T, E> other) → Result<T, E>
Combines two already-evaluated results using the or operator (|).
inherited