ValueWrapper<T> class

A wrapper that disambiguates null from the absence of a value in copyWith methods.

Passing ValueWrapper(null) explicitly signals "set this field to null", whereas omitting the parameter means "leave this field unchanged".

class MyObject {
  final String? name;

  MyObject({this.name});

  MyObject copyWith({ValueWrapper<String?>? name}) {
    return MyObject(
      name: name != null ? name.value : this.name,
    );
  }
}

final original = MyObject(name: 'Initial Name');
// Do not update the name.
final notUpdated = original.copyWith();
print(notUpdated.name); // 'Initial Name'

// Explicitly set the name to null.
final updatedToNull = original.copyWith(name: ValueWrapper(null));
print(updatedToNull.name); // null

Constructors

ValueWrapper(T value)
Wraps value to distinguish an explicit null from an omitted parameter.
const

Properties

hashCode → int
The hash code for this object.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
value → T
The value this wrapper holds.
final

Methods

noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

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