None<T> class final

An Option with no value.

Inheritance

• Object
• Option<T>
• None

Available extensions

• FlattenedOption
• TransposedOption
• UnzippedOption

Constructors

None()

Creates an Option with no value.

const

Properties

flattened → Option<T>

Available on Option<Option<T>>, provided by the FlattenedOption extension

An Option containing another Option flattened into a single Option.

no setter

hashCode → int

The hash code for this object.

no setter, override

isNone → bool

Whether this is a None.

no setter, override

isSome → bool

Whether this is a Some.

no setter, override

iterable → Iterable<T>

Returns an iterable over the possibly contained value.

no setter, override

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

transposed → Result<Option<T>, E>

Available on Option<Result<T, E>>, provided by the TransposedOption extension

An Option containing a Result transposed into a Result containing an Option.

no setter

unzipped → (Option<T>, Option<U>)

Available on Option<(T, U)>, provided by the UnzippedOption extension

An Option containing a tuple transformed into a tuple of two Options.

no setter

valueOrNull → Null

The contained value if this is a Some, or null otherwise.

no setter, override

Methods

and<U>(Option<U> other) → None<U>

Returns other if this is a Some, or None otherwise.

override

andThen<U>(Option<U> calculateOther(T value)) → None<U>

Returns the result of calculateOther if this is a Some, or None otherwise.

override

contains(T value) → bool

Returns true if this is a Some of the given value.

override

inspect(void inspect(T value)) → None<T>

Calls inspect with the contained value if this is a Some.

override

isSomeAnd(bool condition(T value)) → bool

Returns true if this is a Some with a contained value that satisfies condition.

override

map<U>(U map(T value)) → None<U>

Transforms the contained value, if any, by applying map to it.

override

mapOr<U>(U map(T value), U defaultValue) → U

Returns the contained value, if any, with map applied to it, or defaultValue otherwise.

override

mapOrElse<U>(U map(T value), U calculateDefaultValue()) → U

Returns the contained value, if any, with map applied to it, or the result of calculateDefaultValue otherwise.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

okOr<E>(E error) → Err<T, E>

Transforms an Option into a Result, mapping Some to an Ok of the contained value and None to Err of error.

override

okOrElse<E>(E calculateError()) → Err<T, E>

Transforms an Option into a Result, mapping Some to an Ok of the contained value and None to Err of the result of calculateError.

override

or(Option<T> other) → Option<T>

Returns a Some of the original value if this is a Some, or other otherwise.

override

orElse(Option<T> calculateOther()) → Option<T>

Returns a Some of the original value if this is a Some, or the result of calculateOther otherwise.

override

toString() → String

A string representation of this object.

override

unwrap({String? msg}) → Never

Returns the contained value.

override

unwrapOr(T defaultValue) → T

Returns the contained value, if any, or defaultValue otherwise.

override

unwrapOrElse(T calculateDefaultValue()) → T

Returns the contained value, if any, or the result of calculateDefaultValue otherwise.

override

where(bool condition(T value)) → None<T>

Returns a Some of the original value if this is a Some and its contained value satisfies condition, or None otherwise.

override

whereType<U>() → None<U>

Returns a Some of the original value if this is a Some with a contained value of type U, or None otherwise.

override

xor(Option<T> other) → Option<T>

Returns a Some if either, but not both, of this and other is a Some, or None otherwise.

override

zip<U>(Option<U> other) → None<(T, U)>

Returns a tuple of both this and other if both are Some, or None otherwise.

override

zipWith<U, R>(Option<U> other, R zip(T value, U otherValue)) → None<R>

Returns the result of zip called with both this and other if both are Some, or None otherwise.

override

Operators

operator ==(covariant Option<T> other) → bool

The equality operator.

override