Performs additional custom processes before setting a value in the DictionaryBase instance.

[Visual Basic]
Protected Overridable Sub OnSet( _
   ByVal key As Object, _
   ByVal oldValue As Object, _
   ByVal newValue As Object _
)
[C#]
protected virtual void OnSet(
   object key,
   object oldValue,
   object newValue
);
[C++]
protected: virtual void OnSet(
   Object* key,
   Object* oldValue,
   Object* newValue
);
[JScript]
protected function OnSet(
   key : Object,
   oldValue : Object,
   newValue : Object
);

Parameters

key

The key of the element to locate.

oldValue

The old value of the element associated with key.

newValue

The new value of the element associated with key.

Remarks

The default implementation of this method is intended to be overridden by a derived class to perform some action before the specified element is set.

The On* methods are invoked only on the instance returned by the Dictionary property, but not on the instance returned by the InnerHashtable property.

Notes to Implementers:  

This method allows implementers to define processes that must be performed before setting the specified element in the underlying System.Collections.Hashtable. By defining this method, implementers can add functionality to inherited methods without having to override all other methods.

OnSet is invoked before the standard Set behavior, whereas OnSetComplete is invoked after the standard Set behavior.

For example, implementers can restrict which values can be overwritten by performing a check inside OnSet.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

DictionaryBase Class | DictionaryBase Members | System.Collections Namespace | OnSetComplete | OnInsert | OnValidate