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DynamicMethod.CreateDelegate Method (Type, Object)

Completes the dynamic method and creates a delegate that can be used to execute it, specifying the delegate type and an object the delegate is bound to.

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

public Delegate CreateDelegate(
	Type delegateType,
	Object target


Type: System.Type
A delegate type whose signature matches that of the dynamic method, minus the first parameter.
Type: System.Object
An object the delegate is bound to. Must be of the same type as the first parameter of the dynamic method.

Return Value

Type: System.Delegate
A delegate of the specified type, which can be used to execute the dynamic method with the specified target object.


The dynamic method has no method body.


target is not the same type as the first parameter of the dynamic method, and is not assignable to that type.


delegateType has the wrong number of parameters or the wrong parameter types.

This method overload creates a delegate bound to a particular object. Such a delegate is said to be closed over its first argument. Although the method is static, it acts as if it were an instance method; the instance is target.

This method overload requires target to be of the same type as the first parameter of the dynamic method, or to be assignable to that type (for example, a derived class). The signature of delegateType has all the parameters of the dynamic method except the first. For example, if the dynamic method has the parameters String, Int32, and Byte, then delegateType has the parameters Int32 and Byte; target is of type String.

Calling the CreateDelegate method or the Invoke method completes the dynamic method. Any further attempt to alter the dynamic method, such as modifying parameter definitions or emitting more Microsoft intermediate language (MSIL), is ignored; no exception is thrown.

To create a method body for a dynamic method when you have your own MSIL generator, call the GetDynamicILInfo method to obtain a DynamicILInfo object. If you do not have your own MSIL generator, call the GetILGenerator method to obtain an ILGenerator object that can be used to generate the method body.

The following code example creates delegate that binds a DynamicMethod to an instance of a type, so that the method acts on the same instance each time it is invoked.

The code example defines a class named Example with a private field, a class named DerivedFromxample that derives from the first class, a delegate type named UseLikeStatic that returns Int32 and has parameters of type Example and Int32, and a delegate type named UseLikeInstance that returns Int32 and has one parameter of type Int32.

The example code then creates a DynamicMethod that changes the private field of an instance of Example and returns the previous value.


In general, changing the internal fields of classes is not good object-oriented coding practice.

The example code creates an instance of Example and then creates two delegates. The first is of type UseLikeStatic, which has the same parameters as the dynamic method. The second is of type UseLikeInstance, which lacks the first parameter (of type Example). This delegate is created using the CreateDelegate(Type, Object) method overload; the second parameter of that method overload is an instance of Example, in this case the instance just created, which is bound to the newly created delegate. Whenever that delegate is invoked, the dynamic method acts on the bound instance of Example.


This is an example of the relaxed rules for delegate binding introduced in the .NET Framework version 2.0, along with new overloads of the Delegate.CreateDelegate method. For more information, see the Delegate class.

The UseLikeStatic delegate is invoked, passing in the instance of Example that is bound to the UseLikeInstance delegate. Then the UseLikeInstance delegate is invoked, so that both delegates act on the same instance of Example. The changes in the values of the internal field are displayed after each call. Finally, a UseLikeInstance delegate is bound to an instance of DerivedFromxample, and the delegate calls are repeated.

using System;
using System.Reflection;
using System.Reflection.Emit;

// These classes are for demonstration purposes.
public class Example
    private int id = 0;
    public Example(int id)
    { = id;
    public int ID { get { return id; }}

public class DerivedFromExample : Example
    public DerivedFromExample(int id) : base(id) {} 

// Two delegates are declared: UseLikeInstance treats the dynamic
// method as if it were an instance method, and UseLikeStatic
// treats the dynamic method in the ordinary fashion.
public delegate int UseLikeInstance(int newID);
public delegate int UseLikeStatic(Example ex, int newID);

public class Demo
    public static void Main()
        // This dynamic method changes the private id field. It has
        // no name; it returns the old id value (return type int);
        // it takes two parameters, an instance of Example and 
        // an int that is the new value of id; and it is declared 
        // with Example as the owner type, so it can access all 
        // members, public and private.
        DynamicMethod changeID = new DynamicMethod(
            new Type[] { typeof(Example), typeof(int) },

        // Get a FieldInfo for the private field 'id'.
        FieldInfo fid = typeof(Example).GetField(
            BindingFlags.NonPublic | BindingFlags.Instance

        ILGenerator ilg = changeID.GetILGenerator();

        // Push the current value of the id field onto the 
        // evaluation stack. It's an instance field, so load the
        // instance of Example before accessing the field.
        ilg.Emit(OpCodes.Ldfld, fid);

        // Load the instance of Example again, load the new value 
        // of id, and store the new field value. 
        ilg.Emit(OpCodes.Stfld, fid);

        // The original value of the id field is now the only 
        // thing on the stack, so return from the call.

        // Create a delegate that uses changeID in the ordinary
        // way, as a static method that takes an instance of
        // Example and an int.
        UseLikeStatic uls = 
            (UseLikeStatic) changeID.CreateDelegate(

        // Create an instance of Example with an id of 42.
        Example ex = new Example(42);

        // Create a delegate that is bound to the instance of 
        // of Example. This is possible because the first 
        // parameter of changeID is of type Example. The 
        // delegate has all the parameters of changeID except
        // the first.
        UseLikeInstance uli = 
            (UseLikeInstance) changeID.CreateDelegate(

        // First, change the value of id by calling changeID as
        // a static method, passing in the instance of Example.
            "Change the value of id; previous value: {0}",
            uls(ex, 1492)

        // Change the value of id again using the delegate bound
        // to the instance of Example.
            "Change the value of id; previous value: {0}",

        Console.WriteLine("Final value of id: {0}", ex.ID);

        // Now repeat the process with a class that derives
        // from Example.
        DerivedFromExample dfex = new DerivedFromExample(71);

        uli = (UseLikeInstance) changeID.CreateDelegate(

            "Change the value of id; previous value: {0}",
            uls(dfex, 73)
            "Change the value of id; previous value: {0}",
        Console.WriteLine("Final value of id: {0}", dfex.ID);

/* This code example produces the following output:

Change the value of id; previous value: 42
Change the value of id; previous value: 1492
Final value of id: 2700
Change the value of id; previous value: 71
Change the value of id; previous value: 73
Final value of id: 79

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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