Failure<S, E extends Exception> class final

Represents a failed outcome of an operation, containing an error of type E.

This class extends Result and signifies that an operation has failed, yielding an error of type E. The associated success type S is still specified to maintain consistency with the Result interface.

Type Parameters:

  • S: The type of the successful result (not used in this class but required for consistency).
  • E: The type of the error, extending Exception.

Example usage with different error types:

// Example 1: Using Failure with a generic Exception
final result = Failure<int, Exception>(Exception('An error occurred'));
print(result.error); // Output: Exception: An error occurred

// Example 2: Using Failure with a FormatException
final result = Failure<String, FormatException>(FormatException('Invalid format'));
print(result.error); // Output: FormatException: Invalid format

// Example 3: Using Failure with a custom DatabaseException
final result = Failure<List<double>, DatabaseException>(DatabaseException('Database error'));
print(result.error.message); // Output: Database error

// Example 4: Using Failure with a TimeoutException
final result = Failure<User, TimeoutException>(TimeoutException('Operation timed out'));
print(result.error.message); // Output: Operation timed out
Inheritance

Constructors

Failure.new(E error)
const

Properties

error → E
The error resulting from a failed operation.
final
errorOrNull → E?
Returns the error if this is a Failure, otherwise returns null.
no setterinherited
hashCode → int
The hash code for this object.
no setterinherited
isFailure → bool
Returns true if this result is a failure.
no setterinherited
isSuccess → bool
Returns true if this result is a success.
no setterinherited
props → List<Object?>
The list of properties that will be used to determine whether two instances are equal.
no setter
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
stringify → bool?
If set to true, the toString method will be overridden to output this instance's props.
no setterinherited
valueOrNull → S?
Returns the success value if this is a Success, otherwise returns null.
no setterinherited

Methods

fold<T>(T onSuccess(S value), T onFailure(E error)) → T
Reduces this Result into a single value. If the result is a Success, the onSuccess function is applied to the value. If it is a Failure, the onFailure function is applied to the error.
override
getOrElse(S defaultValue) → S
Returns the success value if available; otherwise, returns the provided defaultValue.
override
getOrThrow() → S
Returns the success value if this Result is a Success. If this is a Failure, it throws the associated error.
override
map<T>(T mapper(S value)) → Result<T, E>
Transforms the success value of type S using the provided mapper function. If the result is a Success, the mapper is applied; if it's a Failure, the error is preserved.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.

Operators

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