module › Classes › Module

Module abstract

abstract class Module

Base contract for a module in the Modularity framework.

A module is an isolated unit of functionality with its own dependency registrations and lifecycle. Override binds to register private dependencies and exports to expose public ones.

class NetworkModule extends Module {
  @override
  List<Module> get imports => [LoggingModule()];

  @override
  void binds(Binder i) {
    i.registerLazySingleton<HttpClient>(() => HttpClient());
  }

  @override
  void exports(Binder i) {
    i.registerFactory<ApiClient>(
      () => ApiClient(i.get<HttpClient>()),
    );
  }

  @override
  Future<void> onInit() async {
    // Perform async setup after all dependencies are registered.
  }
}

See also:

• Binder for the dependency registration API.
• Configurable for modules that accept runtime configuration.
• ModuleStatus for the lifecycle state machine.

Implementers

• RetentionIdentityProvider

Constructors

Module()

Module()

Properties

expects no setter

List<Type> get expects

Types that the parent scope must provide.

Checked at startup before binds runs. If any listed type is missing from the parent scope or imports, initialization fails with ModuleConfigurationException.

Implementation

List<Type> get expects => [];

hashCode no setter inherited

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

Implementation

external int get hashCode;

imports no setter

List<Module> get imports

Modules that this module depends on.

Imports are resolved and initialized before this module's binds is called. Their exported dependencies become available through the binder's import chain.

Implementation

List<Module> get imports => [];

runtimeType no setter inherited

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

submodules no setter

List<Module> get submodules

Structural sub-features that compose this module.

Used for static analysis and visualization only (e.g. by modularity_cli). Submodules listed here should implement Configurable for runtime parameters instead of relying on constructor arguments.

Implementation

List<Module> get submodules => [];

Methods

binds()

void binds(Binder i)

Registers dependencies available only within this module.

Place internal implementations, data sources, and mappers here. These dependencies are invisible to modules that import this one.

Implementation

void binds(Binder i);

exports()

void exports(Binder i)

Registers dependencies that this module exports to importers.

Only public interfaces and facades should be registered here. The binder is in export mode, so registrations go to the public scope.

Implementation

void exports(Binder i) {}

hotReload()

void hotReload(Binder i)

Hot-reload hook.

Called during Flutter hot reload to allow updating factory closures without losing singleton state. The binder runs under RegistrationStrategy.preserveExisting when this hook is invoked.

Implementation

void hotReload(Binder i) {}

noSuchMethod() inherited

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

onDispose()

void onDispose()

Resource cleanup hook.

Called when the module is being disposed. Release connections, cancel subscriptions, or perform other cleanup here.

Implementation

void onDispose() {}

onInit()

Future<void> onInit()

Asynchronous initialization hook.

Called after all imports have reached ModuleStatus.loaded and after binds and exports have been executed. Use this to perform async setup such as opening database connections or pre-loading caches.

Implementation

Future<void> onInit() async {}

toString() inherited

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

Implementation

external String toString();

Operators

operator ==() inherited

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

Implementation

external bool operator ==(Object other);