None<T> class final

Represents the absence of a value.

final none = None<int>();
print(none.isNone); // true

Inheritance

• Object
• Option<T>
• None

Constructors

None()

Creates a None instance.

const

Properties

hashCode → int

The hash code for this object.

no setter, override

isNone → bool

Returns true if this is None.

no setter, inherited

isSome → bool

Returns true if this is Some.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

filter(bool predicate(T t)) → Option<T>

Returns this Option if it is Some and predicate returns true. Otherwise returns None.

override

flatMap<R>(Option<R> f(T t)) → Option<R>

Chains a computation that returns an Option, avoiding nesting.

override

fold<W>(W onNone(), W onSome(T t)) → W

Applies onNone if this is None, or onSome if this is Some.

override

getOrElse(T defaultValue()) → T

Returns the contained value if Some, otherwise returns defaultValue.

override

map<R>(R f(T t)) → Option<R>

Transforms the contained value using f if this is Some.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

tap(void action(T t)) → Option<T>

Executes action if this is Some, then returns this unchanged.

override

toNullable() → T?

Returns the contained value if Some, otherwise returns null.

override

toResult<L>(L onNone()) → Result<L, T>

Converts this Option to a Result.

override

toString() → String

A string representation of this object.

override

Operators

operator ==(Object other) → bool

The equality operator.

override