Delegate.Combine Method (Delegate, Delegate)
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Concatenates the invocation lists of two delegates.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- a
- Type: System.Delegate
The delegate whose invocation list comes first.
- b
- Type: System.Delegate
The delegate whose invocation list comes last.
Return Value
Type: System.DelegateA new delegate with an invocation list that concatenates the invocation lists of a and b in that order. Returns a if b is Nothing, returns b if a is a null reference, and returns a null reference if both a and b are null references.
| Exception | Condition |
|---|---|
| ArgumentException | Both a and b are not Nothing, and a and b are not instances of the same delegate type. |
| MethodAccessException | 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.