NotifyPropertyChangedAttribute Class

Custom attribute that, when applied on a type, implements the INotifyPropertyChanged interface for this class and all children classes.

Inheritance Hierarchy

System.Object
  System.Attribute
    PostSharp.Extensibility.MulticastAttribute
      PostSharp.Aspects.Aspect
        PostSharp.Aspects.TypeLevelAspect
          PostSharp.Aspects.InstanceLevelAspect
            PostSharp.Patterns.Model.NotifyPropertyChangedAttribute

Namespace: PostSharp.Patterns.Model
Assembly: PostSharp.Patterns.Model (in PostSharp.Patterns.Model.dll) Version: 2023.0.3.0 (2023.0.3.0)

Syntax

Copy

public sealed class NotifyPropertyChangedAttribute : InstanceLevelAspect, 
	ISerializationCallback, INotifyPropertyChanged, IAdviceProvider, IAspect, IQueryInterface, 
	IDynamicInterfaceImplementation

The NotifyPropertyChangedAttribute type exposes the following members.

Constructors

	Name	Description
	NotifyPropertyChangedAttribute	Initializes a new instance of the NotifyPropertyChangedAttribute class that stores strong references to the client delegates.

Properties

	Name	Description
	AspectPriority	Gets or sets the weaving priority of the aspect. (Inherited from Aspect.)
	AttributeExclude	If true, indicates that this attribute removes all other instances of the same attribute type from the set of elements defined by the current instance. (Inherited from MulticastAttribute.)
	AttributeInheritance	Determines whether this attribute is inherited (Inherited from MulticastAttribute.)
	AttributePriority	Gets or sets the priority of the current attribute in case that multiple instances are defined on the same element (lower values are processed before). (Inherited from MulticastAttribute.)
	AttributeReplace	Determines whether this attribute replaces other attributes found on the target declarations. (Inherited from MulticastAttribute.)
	AttributeTargetAssemblies	Gets or sets the assemblies to which the current attribute apply. (Inherited from MulticastAttribute.)
	AttributeTargetElements	Gets or sets the kind of elements to which this custom attributes applies. (Inherited from MulticastAttribute.)
	AttributeTargetExternalMemberAttributes	Gets or sets the visibilities, scopes, virtualities, and implementation of members to which this attribute applies, when the member is external to the current module. (Inherited from MulticastAttribute.)
	AttributeTargetExternalTypeAttributes	Gets or sets the visibilities of types to which this attribute applies, when this type is external to the current module. (Inherited from MulticastAttribute.)
	AttributeTargetMemberAttributes	Gets or sets the visibilities, scopes, virtualities, and other characteristics of members to which this attribute applies. (Inherited from MulticastAttribute.)
	AttributeTargetMembers	Gets or sets the expression specifying to which members this instance applies. (Inherited from MulticastAttribute.)
	AttributeTargetParameterAttributes	Gets or sets the passing style (by value, out or ref) of parameters to which this attribute applies. (Inherited from MulticastAttribute.)
	AttributeTargetParameters	Gets or sets the expression specifying to which parameters this instance applies. (Inherited from MulticastAttribute.)
	AttributeTargetTypeAttributes	Gets or sets the attributes of types to which this attribute applies. Visibility, scope (Instance or Static) and generation are the only categories that are taken into account; attributes of other categories are ignored. (Inherited from MulticastAttribute.)
	AttributeTargetTypes	Gets or sets the expression specifying to which types this instance applies. (Inherited from MulticastAttribute.)
	ExcludeExplicitProperties	Determines whether the aspect should instrument only automatic properties and ignore any other. This mode allows to use only the abilities of PostSharp Essentials, and prevent the aspect from consuming premium features.
	Instance	Gets the object to which the current aspect has been applied. (Inherited from InstanceLevelAspect.)
	PreventFalsePositives	Determines whether the aspect should do additional efforts to prevent the PropertyChanged event from being raised when the value itself did not change. The default value of this property is false, which means that the aspect will raise the PropertyChanged event whenever any dependency of the property has changed, whether the property value has eventually changed or not. Setting this property to true consumes more memory and processing power because the aspect will need to evaluate the properties and store their value.
	UnsupportedTargetAction	Specifies the action to take when the aspect is applied to an unsupported target element. This property affects only simple aspects, not composite aspects. (Inherited from Aspect.)
	WeakEventStrategy	Determines how the PropertyChanged event behaves in terms of keeping weak or strong references.

Methods

	Name	Description
	CompileTimeInitialize	Method invoked at build time to initialize the instance fields of the current aspect. This method is invoked before any other build-time method. (Overrides TypeLevelAspect.CompileTimeInitialize(Type, AspectInfo).)
	CompileTimeValidate(Object)	Method invoked at build time to ensure that the aspect has been applied to the right target. (Inherited from TypeLevelAspect.)
	CompileTimeValidate(Type)	Method invoked at build time to ensure that the aspect has been applied to the right target. (Overrides TypeLevelAspect.CompileTimeValidate(Type).)
	CreateInstance	Creates a new instance of the aspect based on the current instance, serving as a prototype. (Overrides InstanceLevelAspect.CreateInstance(AdviceArgs).)
	Finalize	Destructor. (Overrides Object.Finalize().)
	GetAspectConfiguration	Method invoked at build tome to get the imperative configuration of the current Aspect. (Inherited from Aspect.)
	OnCloned	Method called after the an object enhanced by the current aspect has been cloned using MemberwiseClone(). The this parameter refers to the new aspect instance in the cloned object. (Overrides InstanceLevelAspect.OnCloned(ICloneAwareAspect).)

Remarks

The aspect analyzes dependencies between property getters and fields. The aspect understands indirect dependencies. For instance, a property getter may depend on several other methods or property getters, which in turn can depend on other methods or fields. The algorithm is not able to analyze calls to virtual methods or delegates (because of prohibitive computational cost), and will only try to analyze methods in the current class.

The aspect will emit a build-time error if it is not able to understand the code of the target class. In this case, you can exclude the property from automatic change notification by applying the IgnoreAutoChangeNotificationAttribute custom attribute to the problematic property, or SafeForDependencyAnalysisAttribute to ignore the warnings of the dependency analysis engine. You will then need to specify dependencies explicitly using the Depends class. You can also mark a helper method with the PureAttribute to make it safe from use in a property getter. For instance, the string.Format method is pure.

By default, the NotifyPropertyChangedAttribute aspect holds weak references to the client delegates. This behavior prevents memory leaks if client delegates are not properly removed before client objects are disposed. To cause the aspect to store strong references, set WeakEventStrategy property to AlwaysStrong when applying the aspect.

Target classes can customize the NotifyPropertyChangedAttribute aspect by implementing the OnPropertyChanged(string) method manually. If this method is implemented, it must be protected or public.

By default, the NotifyPropertyChangedAttribute aspect does not call property getters by itself in order to avoid unexpected side-effects. However, this means that there are false positive notifications of property change. To allow aspect to use arbitrary calls to property getters to suppress false positives, set the PreventFalsePositives property to true.