Gemstone Common Library
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# CollectionExtensionsAddOrUpdate TKey, TValue(IDictionary TKey, TValue, TKey, Func TKey, TValue, Func TKey, TValue, TValue) Method

Adds a key/value pair to the IDictionaryTKey, TValue if the key does not already exist, or updates a key/value pair in the IDictionaryTKey, TValue if the key already exists.

## Definition

Namespace: Gemstone.Collections.CollectionExtensions
Assembly: Gemstone.Common (in Gemstone.Common.dll) Version: 1.0.154 -- Release Build+24a4f4795f9fb8aaeeb777ef1e3e0158effe5bad
C#
View Source Request Example

    public static TValue AddOrUpdate<TKey, TValue>(
    	this IDictionary<TKey, TValue> dictionary,
    	TKey key,
    	Func<TKey, TValue> addValueFactory,
    	Func<TKey, TValue, TValue> updateValueFactory
    )

VB
View Source Request Example

    <ExtensionAttribute>
    Public Shared Function AddOrUpdate(Of TKey, TValue) (
    	dictionary As IDictionary(Of TKey, TValue),
    	key As TKey,
    	addValueFactory As Func(Of TKey, TValue),
    	updateValueFactory As Func(Of TKey, TValue, TValue)
    ) As TValue

C++
View Source Request Example

    public:
    [ExtensionAttribute]
    generic<typename TKey, typename TValue>
    static TValue AddOrUpdate(
    	IDictionary<TKey, TValue>^ dictionary,
    	TKey key,
    	Func<TKey, TValue>^ addValueFactory,
    	Func<TKey, TValue, TValue>^ updateValueFactory
    )

JavaScript
View Source Request Example

    JavaScript does not support generic types or methods.

#### Parameters

dictionary IDictionary TKey, TValue
  The dictionary to add the key/value pair to if the key does not already exist.
key TKey
  The key to be added or whose value should be updated
addValueFactory Func TKey, TValue
  The function used to generate a value for an absent key
updateValueFactory Func TKey, TValue, TValue
  The function used to generate a new value for an existing key based on the key's existing value

#### Type Parameters

TKey
  The type of the keys in the dictionary.
TValue
  The type of the values in the dictionary.

#### Return Value

TValue
The new value for the key. This will be either be the result of addValueFactory (if the key was absent) or the result of updateValueFactory (if the key was present).

#### Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IDictionary TKey, TValue. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

## See Also

#### Reference

CollectionExtensions Class
AddOrUpdate Overload
Gemstone.Collections.CollectionExtensions Namespace