DeclareParents class

Makes the proxies of matching beans implement an extra interface, with an implementation the aspect supplies (an AspectJ "introduction").

Use it to add a capability to many beans without changing their classes, for example a usage counter every service can report. Put it on a static field of an @Aspect class: the field's type is the interface to add. The proxy of every bean whose class matches the value type pattern (Orders, *Service, Repository+) then implements it and forwards its members to a defaultImpl instance, created once per proxy on first use. Only beans of the aspect's own module get the interface, and only while the aspect is registered. Advice can receive the introduced object with this(name).

@Aspect()
@Component()
class UsageTracking {
  // Every *Service bean also implements UsageTracked.
  @DeclareParents('*Service+', defaultImpl: DefaultUsageTracked)
  static UsageTracked? mixin;

  // Each service call bumps that service's own counter.
  @Before('execution(* *Service.*(..)) && this(usage)')
  void count(UsageTracked usage) => usage.increment();
}

// Elsewhere: read the counter through the introduced interface.
final usage = context.getBean<OrderService>() as UsageTracked;

Spring (Java):

@DeclareParents(value = "com.x.service.*+",
    defaultImpl = DefaultUsageTracked.class)
public static UsageTracked mixin;

Constructors

DeclareParents(String value, {required Type defaultImpl})

Adds the field's interface to the proxies of beans matching value, implemented by defaultImpl.

const

Properties

defaultImpl → Type

The class implementing the interface; it needs a constructor without arguments. Each proxy gets its own instance.

final

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

value → String

The type pattern of the bean classes that get the interface: a name with * wildcards, and + for the type and its subtypes.

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