View source for System.Classes.TComponent.ReferenceInterface

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==Description==
{{#ifeq: {{PAGENAME}} | System.Classes.TComponent.ReferenceInterface | |{{InheritsFrom|System.Classes.TComponent.ReferenceInterface}}}}

<section begin=short />Establishes or removes internal links that cause this component to be notified when the implementer of a specified interface is destroyed.<section end=short />

Component writers use [[System.Classes.TComponent.ReferenceInterface|ReferenceInterface]] to ensure that properties whose values are interfaces are informed when the objects that implement those interfaces are destroyed. This notification must be in place for a property whose value is an interface to be saved with the component in a form file (that is, for such a property to persist as a published property).

<code>I</code> is an interface pointer that is the value of the published property of interest.

<code>Operation</code> indicates whether the notification link to the implementer of the interface should be established (opInsert) or removed (opRemove).

[[System.Classes.TComponent.ReferenceInterface|ReferenceInterface]] returns '''True''' if it is successful in establishing or removing the notification link. If [[System.Classes.TComponent.ReferenceInterface|ReferenceInterface]] returns '''False''' when called with <code>Operation</code> set to opInsert, the specified interface cannot be stored as the value of a published property.

<blockquote>'''Note:''' A result of '''False''' does not necessarily indicate an error, merely that the interface cannot be stored by the property streaming system. For example, [[System.Classes.TComponent.ReferenceInterface|ReferenceInterface]] returns '''False''' when the specified interface employs true reference counting, independent of component lifetimes.</blockquote>

===See Also===

* [[System.Classes.TComponent.FreeNotification|FreeNotification]]

* [[System.Classes.TComponent.RemoveFreeNotification|RemoveFreeNotification]]


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