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ModuleRetainer ​

class ModuleRetainer

Cache for ModuleController instances with KeepAlive retention policy.

Retention Key vs Override Scope ​

Important: The retainer uses retentionKey for cache lookup, which is independent of ModuleOverrideScope. This is by design:

  • retentionKey determines cache identity (derived from module type, route, arguments, and explicit key).
  • overrideScope affects DI bindings within the module's dependency graph but does NOT affect retention cache identity.

Implications ​

Two ModuleScope widgets of the same module type with:

  • Same retentionKey but different overrideScopes → share the same cached controller. The first scope's overrideScope wins.
  • Different retentionKeys but same overrideScope → have separate cached controllers.

If you need override-aware caching, provide explicit retentionKey that incorporates the scope identity:

dart
ModuleScope(
  module: MyModule(),
  retentionPolicy: ModuleRetentionPolicy.keepAlive,
  retentionKey: 'my-module-${overrideScope.hashCode}',
  overrideScope: overrideScope,
  child: ...,
)

Thread Safety ​

This class is NOT thread-safe. All operations must be performed on the main isolate.

Constructors ​

ModuleRetainer() ​

ModuleRetainer()

Properties ​

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
dart
external int get hashCode;

logger read / write ​

(void Function(ModuleLifecycleEvent event, Type moduleType, {Map<String, Object?>? details, Object? retentionKey}))? logger

getter:

Optional logger for module lifecycle events.

Set by ModularityRoot during initialization and cleared on disposal.

setter:

Optional logger for module lifecycle events.

Set by ModularityRoot during initialization and cleared on disposal.

Implementation
dart
ModuleLifecycleLogger? logger;

runtimeType no setter inherited ​

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation
dart
external Type get runtimeType;

Methods ​

acquire() ​

dynamic acquire(Object key)

Return the cached ModuleController for key and increment its reference count, or null if no entry exists.

Implementation
dart
ModuleController? acquire(Object key) {
  final entry = _entries[key];
  if (entry == null) return null;
  entry.refCount++;
  entry.lastAccessed = DateTime.now();
  _log(
    ModuleLifecycleEvent.reused,
    entry.moduleType,
    retentionKey: key,
    details: {'refCount': entry.refCount},
  );
  return entry.controller;
}

contains() ​

bool contains(Object key)

Return whether a controller with the given key exists in the cache.

Implementation
dart
bool contains(Object key) => _entries.containsKey(key);

debugSnapshot() ​

List<ModuleRetainerEntrySnapshot> debugSnapshot()

Return a list of ModuleRetainerEntrySnapshot instances reflecting the current cache state, intended for debugging and testing.

Implementation
dart
List<ModuleRetainerEntrySnapshot> debugSnapshot() {
  return _entries.entries
      .map(
        (e) => ModuleRetainerEntrySnapshot(
          key: e.key,
          policy: e.value.policy,
          refCount: e.value.refCount,
          lastAccessed: e.value.lastAccessed,
          moduleType: e.value.moduleType,
        ),
      )
      .toList(growable: false);
}

evict() ​

Future<void> evict(Object key, {bool disposeController = true})

Remove the entry for key from the cache regardless of reference count.

When disposeController is true (the default), the underlying ModuleController is disposed after removal.

Implementation
dart
Future<void> evict(Object key, {bool disposeController = true}) async {
  final entry = _entries.remove(key);
  if (entry == null) return;
  _log(
    ModuleLifecycleEvent.evicted,
    entry.moduleType,
    retentionKey: key,
    details: {'disposeController': disposeController},
  );
  if (disposeController) {
    await entry.dispose();
    _log(
      ModuleLifecycleEvent.disposed,
      entry.moduleType,
      retentionKey: key,
      details: {'reason': 'evicted'},
    );
  }
}

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:

dart
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:

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

peek() ​

dynamic peek(Object key)

Return the cached ModuleController for key without incrementing the reference count, or null if no entry exists.

Implementation
dart
ModuleController? peek(Object key) => _entries[key]?.controller;

register() ​

void register({required Object key, required dynamic controller, dynamic policy = ModuleRetentionPolicy.keepAlive, int initialRefCount = 1, dynamic route, (FutureOr<void> Function())? onRouteTerminated})

Register a ModuleController in the cache under key.

Throw ModuleLifecycleException if key is already registered. Optionally attach a route so the entry is automatically evicted when the route is popped, invoking onRouteTerminated as a callback.

Implementation
dart
void register({
  required Object key,
  required ModuleController controller,
  ModuleRetentionPolicy policy = ModuleRetentionPolicy.keepAlive,
  int initialRefCount = 1,
  ModalRoute<dynamic>? route,
  FutureOr<void> Function()? onRouteTerminated,
}) {
  if (_entries.containsKey(key)) {
    throw ModuleLifecycleException(
      'Retention key "$key" is already registered. '
      'Call release&#47;evict before registering again.',
      moduleType: controller.module.runtimeType,
    );
  }
  final entry = _ModuleRetainerEntry(
    retainer: this,
    controller: controller,
    policy: policy,
    lastAccessed: DateTime.now(),
    refCount: initialRefCount,
    route: route,
    onRouteTerminated: onRouteTerminated,
  );
  _entries[key] = entry;
  _log(
    ModuleLifecycleEvent.registered,
    controller.module.runtimeType,
    retentionKey: key,
    details: {
      'policy': policy.name,
      'refCount': initialRefCount,
      'hasRoute': route != null,
    },
  );
}

release() ​

Future<void> release(Object key, {bool disposeIfOrphaned = false})

Decrement the reference count for key.

If disposeIfOrphaned is true and the reference count drops to zero, remove the entry and dispose its ModuleController.

Implementation
dart
Future<void> release(Object key, {bool disposeIfOrphaned = false}) async {
  final entry = _entries[key];
  if (entry == null) return;
  if (entry.refCount > 0) {
    entry.refCount--;
  }
  _log(
    ModuleLifecycleEvent.released,
    entry.moduleType,
    retentionKey: key,
    details: {
      'refCount': entry.refCount,
      'disposeIfOrphaned': disposeIfOrphaned,
    },
  );
  if (disposeIfOrphaned && entry.refCount <= 0) {
    final removed = _entries.remove(key) ?? entry;
    await removed.dispose();
    _log(
      ModuleLifecycleEvent.disposed,
      removed.moduleType,
      retentionKey: key,
      details: {'reason': 'orphaned'},
    );
  }
}

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
dart
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
dart
external bool operator ==(Object other);