None<T> class

None is a type that represents not having a value.

Inheritance
Annotations
  • @sealed

Constructors

None()
const

Properties

hashCode → int
The hash code for this object.
no setteroverride
isNone → bool
Returns true if the option is None.
no setterinherited
isSome → bool
Returns true if the option is Some.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

and<U>(Option<U> optb) → Option<U>
Returns None if the option is None, otherwise returns optb.
inherited
andThen<U>(Option<U> f(T value)) → Option<U>
Returns None if the option is None, otherwise calls f with the wrapped value and returns the result.
inherited
expect(String msg) → T
Returns the contained Some value, consuming the this value.
inherited
filter(bool predicate(T value)) → Option<T>
Returns None if the option is None, otherwise calls predicate with the wrapped value and returns:
inherited
iter() → Iterable<T>
Returns an iterable over the possibly contained value.
inherited
map<U>(U op(T value)) → Option<U>
Maps an Option<T> to Option<U> by applying a function to a contained value.
inherited
mapOr<U>(U defaultValue, U f(T value)) → U
Returns the provided default (if None), or applies a function to the contained value (if Some),
inherited
mapOrElse<U>(U defaultF(), U f(T value)) → U
Computes a default function result (if None), or applies a different function to the contained value (if Some).
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
okOr<E>(E err) → Result<T, E>
Transforms the Option into a Result, mapping Some(v) to Ok(v) and None to Err(err).
inherited
okOrElse<E>(E err()) → Result<T, E>
Transforms the Option into a Result, mapping Some(v) to Ok(v) and None to Err(err()).
inherited
or(Option<T> optb) → Option<T>
Returns the option if it contains a value, otherwise returns optb.
inherited
orElse(Option<T> f()) → Option<T>
Returns the option if it contains a value, otherwise calls f and returns the result.
inherited
some() → T?
Converts from Option<T> to T?.
inherited
toString() → String
A string representation of this object.
override
unwrap() → T
Returns the contained Some value, consuming the this value.
inherited
unwrapOr(T defaultValue) → T
Returns the contained Some value or a provided default.
inherited
unwrapOrElse(T op()) → T
Returns the contained Some value or computes it from a closure.
inherited
xor(Option<T> optb) → Option<T>
Returns Some if exactly one of this, optb is Some, otherwise returns None.
inherited
zip<U>(Option<U> other) → Option<Tuple2<T, U>>
Zips this with another Option.
inherited

Operators

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