Option<T> class abstract

Option is a type that represents either some value (Some) or none (None).

Option<T> is the type used for returning an optional value. It is an object with a Some value, and None, representing no value.

Implementers

Constructors

Option()
const
Option.from(T? v)
Create a option from a nullable value.
factory
Option.none()
Create a None option with no value.
factory
Option.some(T v)
Create a Some option with the given value.
factory

Properties

hashCode → int
The hash code for this object.
no setterinherited
props → List<Object?>
The list of properties that will be used to determine whether two instances are equal.
no setterinherited
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

Methods

and(Option<T> optb) → Option<T>
Returns None if the option is None, otherwise returns optb.
andThen(Option<T> op(T)) → Option<T>
Returns None if the option is None, otherwise calls op with the wrapped value and returns the result.
expect(String msg) → T
Unwraps an option, yielding the content of a Some.
filter(bool predicate(T)) → Option<T>
Returns None if the option is None, otherwise calls predicate with the wrapped value and returns:
isNone() → bool
Returns true if the option is a None value.
isSome() → bool
Returns true if the option is a Some value.
map<U>(U op(T)) → Option<U>
Maps an Option<T> to Option<U> by applying a function to a contained Some value. Otherwise returns a None.
mapOr<U>(U op(T), U opt) → U
Applies a function to the contained value (if any), or returns the provided default (if not).
mapOrElse<U>(U op(T), U def()) → U
Maps an Option<T> to U by applying a function to a contained T value, or computes a default (if not).
match<R>(R someop(T), R noneop()) → R
Invokes either the someop or the noneop depending on the option.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
okOr<E>(E err) → Result<T, E>
Transforms the Option<T> into a Result<T, E>, mapping Some(v) to Ok(v) and None to Err(err).
okOrElse<E>(E err()) → Result<T, E>
Transforms the Option<T> into a Result<T, E>, mapping Some(v) to Ok(v) and None to Err(err()).
or(Option<T> optb) → Option<T>
Returns the option if it contains a value, otherwise returns optb.
orElse(Option<T> op()) → Option<T>
Returns the option if it contains a value, otherwise calls op and returns the result.
toNullable() → T?
Returns an nullable that represents this optional value.
toString() → String
A string representation of this object.
inherited
unwrap() → T
Unwraps an option, yielding the content of a Some.
unwrapOr(T opt) → T
Returns the contained value or a default.
unwrapOrElse(T op()) → T
Returns the contained value or computes it from a closure.
when<R>({required R some(T), required R none()}) → R
Invokes either some or none depending on the option.
xor(Option<T> optb) → Option<T>
Returns Some if exactly one of this, optb is Some, otherwise returns None.

Operators

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