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 setter, inherited

defaultValueMirror → InstanceMirror

InstanceMirror for the default value.

no setter, inherited

equality → Equality

Equality for the kind;

no setter, inherited

examples → Iterable<T>

Examples of instances that are valid (isValidDynamic).

no setter, inherited

examplesThatAreInvalid → Iterable<T>

Examples of instances that are NOT valid (isValidDynamic).

no setter, inherited

examplesWithoutValidation → Iterable<T>

Interesting examples of instances (may be valid or invalid).

no setter, override

hashCode → int

The hash code for this object.

no setter, override

isNullable → bool

Whether this kind is nullable.

no setter, inherited

isPrimitive → bool

Whether instances of the kind can't have references to other instances.

no setter, inherited

isSealed → bool

Whether subclasses are possible;

final

jsonName → String?

JSON identifier of the class.

final, inherited

name → String

Dart identifier of the class.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

traits → List<Trait>

Traits of the kind.

final, inherited

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