Option<T> class sealed

A type that represents the presence (Some) or absence (None) of a value.

Pattern matching is recommended for working with Option types.

Option<int> foo = Some(42);

print(switch (foo) {
  Some(value: var bar) => 'Some value: $bar',
  None() => 'No value!'
});

Constructors

Option.from(T? value): Creates an Option from the given nullable T value.
factory

Properties

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

Methods

and(Option other) → Option: Returns None if this Option is None<T>, otherwise returns other.
andThen(Option fn(T)) → Option: Returns None if this Option is None<T>, otherwise calls fn with the held value and returns the returned Option.
expect(String message) → T: Returns the held value of this Option if it is Some, or throws OptionError with the given message if this Option is None.
inspect(void fn(T)) → Option<T>: Calls the provided function with the contained value if this Option is Some.
isNone() → bool: Returns whether or not this Option holds no value (None).
isSome() → bool: Returns whether or not this Option holds a value (Some).
isSomeAnd(bool predicate(T)) → bool: Returns whether or not this Option holds a value (Some) and the held value matches the given predicate.
iter() → Iterable<T>: Returns an Iterable of the held value.
map(U mapFn(T)) → Option: Maps this Option<T> to an Option using the given function with the held value.
mapOr(U orValue, U mapFn(T)) → Option: Maps this Option<T> to an Option using the given function with the held value if this Option<T> is Some. Otherwise returns the provided orValue as Some(orValue).
mapOrElse(U orFn(), U mapFn(T)) → Option: Maps this Option<T> to an Option using the given mapFn function with the held value if this Option is Some. Otherwise returns the result of orFn as Some(orFn()).
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
okOr<E>(E err) → Result<T, E>: Converts this Option<T> into a Result<T, E> using the given err if None.
okOrElse<E>(E elseFn()) → Result<T, E>: Converts this Option<T> into a Result<T, E> using the returned value from elseFn if None.
or(Option<T> other) → Option<T>: Returns this Option if this Option is Some<T>, otherwise returns other.
orElse(Option<T> fn()) → Option<T>: Returns this Option if this Option is Some<T>, otherwise calls fn and returns the returned Option.
toString() → String: A string representation of this object.
override
unwrap() → T: Returns the held value of this Option if it is Some.
unwrapOr(T orValue) → T: Returns the held value of this Option if it is Some, or the given value if this Option is None.
unwrapOrElse(T elseFn()) → T: Returns the held value of this Option if it is Some, or returns the returned value from elseFn if this Option is None.
where(bool predicate(T)) → Option<T>: Filters this Option based on the given predicate function.
xor(Option<T> other) → Option<T>: Returns Some if exactly one of this Option and other is Some, otherwise returns None.
zip(Option other) → Option<(T, U)>: Zips this Option with another Option, returning a Record of their held values.
zipWith<U, V>(Option other, V zipFn(T, U)) → Option<V>: Zips this Option with another Option using the given function.

Operators

operator ==(Object other) → bool: Compare equality between two Option values.
override
operator ~() → T: Shortcut to call Option.unwrap().

Option<T> class sealed

Constructors

Properties

Methods

Operators

option library