Adds an entry using key and value pair and absolute expiration date into the cache, and returns an existing cache entry with a matching key. 

 
            
            
            
            
            
            
            
            public abstract object AddOrGetExisting( 
   string ,
   object ,
   DateTime ,
   string 
)
             
        
            
            'Declaration
 
Public Overloads MustOverride Function AddOrGetExisting( _
   ByVal  As String, _
   ByVal  As Object, _
   ByVal  As Date, _
   ByVal  As String _
) As Object
             
        
            
            'Usage
 
Dim instance As ObjectCache
Dim key As String
Dim value As Object
Dim absoluteExpiration As Date
Dim regionName As String
Dim value As Object
 
value = instance.AddOrGetExisting(key, value, absoluteExpiration, regionName)
             
        
            
            
            
        
            
            
            
        
            
            public:
abstract Object^ AddOrGetExisting( 
   String^ ,
   Object^ ,
   DateTime ,
   String^ 
) 
             
        
             
        
            Parameters
- key
 
- Unique identifier of the cache item.
 - value
 
- Data for the cache item.
 - absoluteExpiration
 
- Absolute expiration date to use.
 - regionName
 
- Optional name of a region in cache.
 
            
            Return Value
The previous cache entry that matches the specified key, if found. If the cache contains an item with the same key, then it will be returned before it is overwritten. Otherwise, null.