Delegate.Combine Method
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Concatenates the invocation lists of the specified multicast (combinable) delegates.
| Combine(Delegate[]) |
Concatenates the invocation lists of an array of delegates. |
| Combine(ReadOnlySpan<Delegate>) |
Concatenates the invocation lists of an span of delegates. |
| Combine(Delegate, Delegate) |
Concatenates the invocation lists of two delegates. |
- Source:
- Delegate.cs
- Source:
- Delegate.cs
- Source:
- Delegate.cs
Concatenates the invocation lists of an array of delegates.
public:
static Delegate ^ Combine(... cli::array <Delegate ^> ^ delegates);public:
static Delegate ^ Combine(cli::array <Delegate ^> ^ delegates);public static Delegate Combine(params Delegate[] delegates);public static Delegate? Combine(params Delegate?[]? delegates);public static Delegate Combine(Delegate[] delegates);[System.Runtime.InteropServices.ComVisible(true)]
public static Delegate Combine(params Delegate[] delegates);static member Combine : Delegate[] -> Delegate[<System.Runtime.InteropServices.ComVisible(true)>]
static member Combine : Delegate[] -> DelegatePublic Shared Function Combine (ParamArray delegates As Delegate()) As DelegatePublic Shared Function Combine (delegates As Delegate()) As DelegateParameters
- delegates
- Delegate[]
The array of delegates to combine.
Returns
A new delegate with an invocation list that concatenates the invocation lists of the delegates in the delegates array. Returns null if delegates is null, if delegates contains zero elements, or if every entry in delegates is null.
- Attributes
Exceptions
Not all the non-null entries in delegates are instances of the same delegate type.
Remarks
If the delegates array contains entries that are null, those entries are ignored.
The invocation list can contain duplicate entries; that is, entries that refer to the same method on the same object.
Note
Generic delegates that are assignment-compatible because of variance are not necessarily combinable. To be combinable, the types must match exactly. For example, suppose that a class named Derived is derived from a class named Base. A delegate of type Action<Base> (Action(Of Base) in Visual Basic) can be assigned to a variable of type Action<Derived>, as explained in Covariance and Contravariance, but the two delegates cannot be combined because the types do not match exactly.
Combine is useful for creating event handlers that call multiple methods each time an event occurs.
See also
Applies to
.NET 10 and other versions
| Product | Versions |
|---|---|
| .NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1 |
| UWP | 10.0 |
Concatenates the invocation lists of an span of delegates.
public:
static Delegate ^ Combine(ReadOnlySpan<Delegate ^> delegates);public static Delegate? Combine(scoped ReadOnlySpan<Delegate?> delegates);static member Combine : ReadOnlySpan<Delegate> -> DelegatePublic Shared Function Combine (delegates As ReadOnlySpan(Of Delegate)) As DelegateParameters
- delegates
- ReadOnlySpan<Delegate>
The span of delegates to combine.
Returns
A new delegate with an invocation list that concatenates the invocation lists of the delegates in the delegates span.
Returns null if delegates is null, if delegates contains zero elements, or if every entry in delegates is null.
Applies to
.NET 10 and .NET 9
| Product | Versions |
|---|---|
| .NET | 9, 10 |
- Source:
- Delegate.cs
- Source:
- Delegate.cs
- Source:
- Delegate.cs
Concatenates the invocation lists of two delegates.
public:
static Delegate ^ Combine(Delegate ^ a, Delegate ^ b);public static Delegate Combine(Delegate a, Delegate b);public static Delegate? Combine(Delegate? a, Delegate? b);static member Combine : Delegate * Delegate -> DelegatePublic Shared Function Combine (a As Delegate, b As Delegate) As DelegateParameters
- a
- Delegate
The delegate whose invocation list comes first.
- b
- Delegate
The delegate whose invocation list comes last.
Returns
A new delegate with an invocation list that concatenates the invocation lists of a and b in that order. Returns a if b is null, returns b if a is a null reference, and returns a null reference if both a and b are null references.
Exceptions
Both a and b are not null, and a and b are not instances of the same delegate type.
Remarks
The invocation list can contain duplicate entries; that is, entries that refer to the same method on the same object.
Note
Generic delegates that are assignment-compatible because of variance are not necessarily combinable. To be combinable, the types must match exactly. For example, suppose that a class named Derived is derived from a class named Base. A delegate of type Action<Base> (Action(Of Base) in Visual Basic) can be assigned to a variable of type Action<Derived>, as explained in Covariance and Contravariance, but the two delegates cannot be combined because the types do not match exactly.
Combine is useful for creating event handlers that call multiple methods each time an event occurs.
See also
Applies to
.NET 10 and other versions
| Product | Versions |
|---|---|
| .NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10 |
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1 |
| UWP | 10.0 |
.NET feedback
.NET is an open source project. Select a link to provide feedback: