ImmutableKind<T> class sealed

Kind for immutable objects.

There are four possible constructors:

ImmutableKind
- Use if your class has a const constructor or it is at least deeply immutable.
ImmutableKind.walkable
- Use if your class implements Walkable.
ImmutableKind.withConstructor
- Use if the constructor of your class is not const.
ImmutableKind.jsonSerializable
- Use if your class has a YourClass.fromJson(Map<String, dynamic) factory and you are too lazy to write a mapper function.

Optimization tricks

Use Mapper.canReturnSame in your walk function.
Specify non-null name. Otherwise T.toString() has to be called every time name or jsonName is read.

Example

import 'package:kind/kind.dart';

void main() {
  //
  // Encode/decode JSON trees:
  //
  final company = Company.kind.decodeJsonTree({
    'name': 'Flutter App Development Experts',
    'shareholders': [
      {
        '@type': 'Person',
        'firstName': 'Alice',
        'lastName': 'Smith',
      },
      {
        '@type': 'Person',
        'firstName': 'Bob',
      },
    ],
  });
  print("${company.name} has ${company.shareholders.length} shareholders.");

  //
  // We have `==` and `hashCode` because we extended `HasKind`:
  //
  print(company.shareholders[1] == Person(firstName: 'Bob')); // --> true

  //
  // We have `toString()` because we extended `HasKind`:
  //
  print(company.toString());
  // Prints:
  //   Company(
  //     "Flutter App Development Experts",
  //     shareholders: [
  //       Person(
  //         firstName: 'John',
  //         lastName: 'Doe',
  //       ),
  //       Person(firstName: 'Bob'),
  //     ],
  //   )
}

//
// Example class #1:
//   "A static `_walk` function"
//
class Company extends Shareholder {
  static const kind = ImmutableKind<Company>(
    name: 'Company',
    blank: Company(''),
    walk: _walk,
  );

  @override
  final String name;

  final List<Shareholder> shareholders;

  const Company(this.name, {this.shareholders = const []});

  @override
  Kind<Company> get runtimeKind => kind;

  static Company _walk(Mapper f, Company t) {
    final name = f.positional(t.name, 'name');
    final shareholders = f(
      t.shareholders,
      'shareholders',
      kind: const ListKind(
        elementKind: Shareholder.kind,
      ),
    );

    // The following is a performance optimization we recommend:
    if (f.canReturnSame) {
      return t;
    }

    // Finally, construct a new instance:
    return Company(
      name,
      shareholders: shareholders,
    );
  }
}

//
// Example #2:
//   "A class that extends `Walkable`"
//
class Person extends Shareholder with Walkable {
  static const kind = ImmutableKind<Person>.walkable(
    name: 'Person',
    blank: Person(firstName: ''),
  );

  /// First name
  final String firstName;

  /// First name
  final String lastName;

  const Person({
    required this.firstName,
    this.lastName = '',
  });

  @override
  String get name => '$firstName $lastName';

  @override
  Kind<Person> get runtimeKind => kind;

  @override
  Person walk(Mapper f) {
    final firstName = f.required(
      this.firstName,
      'firstName',
      kind: const StringKind.singleLineShort(),
    );
    final lastName = f(
      this.lastName,
      'lastName',
      kind: const StringKind.singleLineShort(),
    );
    if (f.canReturnSame) {
      return this;
    }
    return Person(
      firstName: firstName,
      lastName: lastName,
    );
  }
}

//
// Example #3:
//   "A polymorphic class"
//
abstract class Shareholder extends HasKind {
  static const kind = PolymorphicKind<Shareholder>.sealed(
    defaultKinds: [
      Person.kind,
      Company.kind,
    ],
  );

  const Shareholder();

  String get name;
}

Inheritance

Object
Kind<T>
ImmutableKind

Constructors

ImmutableKind({String? name, String? jsonName, required T blank, required WalkFunction<T> walk, Function? fromJson, Object? toJson(T object)?, Map<String, T>? constantsByName}): Constructs a kind for a class that has a constant constructor.
const

factory
ImmutableKind.jsonSerializable({String? name, String? jsonName, Map<String, Kind>? kinds, T walk(Mapper f, T t)?, required T fromJson(Map<String, dynamic> json), Map<String, dynamic> toJson(T object)?, Map<String, T>? constantsByName}): Creates a kind for any JSON-serializable class.
factory
ImmutableKind.walkable({String? name, String? jsonName, required T blank, Function? fromJson, Object? toJson(T object)?, Map<String, T> constantsByName}): Constructs a kind for a class that implements Walkable.
const

factory
ImmutableKind.withConstructor({String? name, String? jsonName, required T constructor(), required WalkFunction<T> walk, Function? fromJson, Object? toJson(T object)?, Map<String, T> constantsByName}): Constructs a kind for a class that has a non-constant constructor.
const

factory

Properties

constantsByName → Map<String, T>: Constant instances.
final
dartType → Type: Type T.
no setterinherited
defaultValueMirror → InstanceMirror: InstanceMirror for the default value.
no setterinherited
equality → Equality: Equality for the kind;
no setterinherited
examples → Iterable<T>: Examples of instances that are valid (isValidDynamic).
no setterinherited
examplesThatAreInvalid → Iterable<T>: Examples of instances that are NOT valid (isValidDynamic).
no setterinherited
examplesWithoutValidation → Iterable<T>: Interesting examples of instances (may be valid or invalid).
no setteroverride
hashCode → int: The hash code for this object.
no setteroverride
isNullable → bool: Whether this kind is nullable.
no setterinherited
isPrimitive → bool: Whether instances of the kind can't have references to other instances.
no setterinherited
isSealed → bool: Whether subclasses are possible;
final
jsonName → String?: JSON identifier of the class.
finalinherited
name → String: Dart identifier of the class.
no setterinherited
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
traits → List<Trait>: Traits of the kind.
finalinherited

Methods

asType(Object? value) → T: Casts value to T.
inherited
checkDeclaration() → void: Checks that the declaration makes sense.
inherited
checkInstance(Object? value) → void: inherited
checkValid(T instance) → void: override
checkValidDynamic(Object? instance) → void: Throws ArgumentError error if instance is not valid (isValidDynamic).
inherited
clone(T instance) → T: Clones the instance.
override
compare(T left, T right) → int: Compares two values.
override
debugString(T instance) → String: Constructs a string for debugging instance.
override
decodeJsonTree(Object? json) → T: Converts json (any JSON tree) to an instance of T.
override
decodeString(String string) → T: Decodes string to an instance of T.
inherited
encodeJsonTree(T instance) → Object?: Converts instance to a JSON tree.
override
encodeString(T instance) → String: Converts instance to a string.
inherited
isDefaultValue(Object? instance) → bool: Determines whether the argument is a default value of this kind.
inherited
isInstance(Object? instance) → bool: Determines whether the argument is an instance of T.
inherited
isInstanceOfList(Object? instance) → bool: Determines whether the argument is an instance of List<T>.
inherited
isInstanceOfSet(Object? instance) → bool: Determines whether the argument is an instance of Set<T>.
inherited
isNullableSubKind(Kind other, {bool andNotEqual = true}) → bool: Tells whether the argument is instance of Kind<T> and dartType values are different.
inherited
isSubKind(Kind other, {bool andNotEqual = true}) → bool: Tells whether the argument is instance of Kind<T> and dartType values are different.
inherited
isValid(T instance) → bool: Tells whether the instance is valid.
override
isValidDynamic(Object? instance) → bool: Tells whether the instance is valid.
inherited
map(Mapper mapper, T object) → T: Maps object to a new instance of T.
mapDefault(Mapper mapper) → T: Maps the default value with the mapper to a new instance of T.
memorySize(T instance) → int: Estimates memory usage of instance.
inherited
memorySizeWith(MemoryCounter counter, T instance) → void: Estimates memory usage with an instance of MemoryCounter.
override
newInstance() → T: Constructs a new instance of the default value.
inherited
newList(int length, {bool growable = true}) → List<T>: Constructs a new list.
inherited
newListFrom(Iterable<T> iterable, {bool growable = true}) → List<T>: Constructs a new list from iterable.
inherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
permute(T instance) → T: Generates another instance with some deterministic function.
override
register() → void: Registers this kind so that it will be visible in Kind.all.
inherited
toList() → Kind<List<T>>: Constructs Kind for List<T>.
inherited
toNonNullable() → Kind<T>: Returns a non-nullable kind.
inherited
toNullable() → Kind<T?>: Constructs Kind for T?.
inherited
toPolymorphic() → PolymorphicKind<T>: Constructs a PolymorphicKind for this kind.
inherited
toSet() → Kind<Set<T>>: Constructs Kind for Set<T>.
inherited
toString() → String: A string representation of this object.
inherited

Operators

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

ImmutableKind<T> class sealed

Optimization tricks

Example

Constructors

Properties

Methods

Operators

kind library