Delegate.Combine Method

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Concatenates the invocation lists of two delegates.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)


Public Shared Function Combine ( _
    a As Delegate, _
    b As Delegate _
) As Delegate
public static Delegate Combine(
    Delegate a,
    Delegate b


Return Value

Type: System.Delegate
A new delegate with an invocation list that concatenates the invocation lists of a and b in that order. Returns a if b is nulla null reference (Nothing in Visual Basic), returns b if a is a null reference, and returns a null reference if both a and b are null references.


Exception Condition

Both a and b are not nulla null reference (Nothing in Visual Basic), and a and b are not instances of the same delegate type.


Application code attempts to access this member late-bound, for example, by using the Type.InvokeMember method.


The invocation list can contain duplicate entries; that is, entries that refer to the same method on the same object.

Combine is useful for creating event handlers that call multiple methods each time an event occurs.

Version Information


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0


For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.