using System; using System.Reflection; using System.Reflection.Emit;
publicclassExample { // Declare delegates that can be used to execute the completed // SquareIt dynamic method. The OneParameter delegate can be // used to execute any method with one parameter and a return // value, or a method with two parameters and a return value // if the delegate is bound to an object. // 1,声明用于执行方法的委托类型。 privatedelegatelongSquareItInvoker(int input);
privatedelegate TReturn OneParameter<TReturn, TParameter0> (TParameter0 p0); publicstaticvoidMain() { // Example 1: A simple dynamic method. // // Create an array that specifies the parameter types for the // dynamic method. In this example the only parameter is an // int, so the array has only one element. // 2,创建用于为动态方法指定参数类型的数组。 Type[] methodArgs = { typeof(int) };
// Create a DynamicMethod. In this example the method is // named SquareIt. It is not necessary to give dynamic // methods names. They cannot be invoked by name, and two // dynamic methods can have the same name. However, the // name appears in calls stacks and can be useful for // debugging. // // In this example the return type of the dynamic method // is long. The method is associated with the module that // contains the Example class. Any loaded module could be // specified. The dynamic method is like a module-level // static method. // 3,创建 DynamicMethod。 DynamicMethod squareIt = new DynamicMethod( "SquareIt", typeof(long), methodArgs, typeof(Example).Module);
// Emit the method body. In this example ILGenerator is used // to emit the MSIL. DynamicMethod has an associated type // DynamicILInfo that can be used in conjunction with // unmanaged code generators. // // The MSIL loads the argument, which is an int, onto the // stack, converts the int to a long, duplicates the top // item on the stack, and multiplies the top two items on the // stack. This leaves the squared number on the stack, and // all the method has to do is return. // 4,发出方法主体。 ILGenerator il = squareIt.GetILGenerator(); il.Emit(OpCodes.Ldarg_0); il.Emit(OpCodes.Conv_I8); il.Emit(OpCodes.Dup); il.Emit(OpCodes.Mul); il.Emit(OpCodes.Ret);
// Create a delegate that represents the dynamic method. // Creating the delegate completes the method, and any further // attempts to change the method (for example, by adding more // MSIL) are ignored. The following code uses a generic // delegate that can produce delegate types matching any // single-parameter method that has a return type. // 5,通过调用 CreateDelegate 方法创建表示动态方法的委托（在步骤 1 中声明）的实例 // 以下代码使用泛型委托创建委托并调用它。 OneParameter<long, int> invokeSquareIt = (OneParameter<long, int>) squareIt.CreateDelegate(typeof(OneParameter<long, int>)); // squared :平方 Console.WriteLine("123456789 squared = {0}", invokeSquareIt(123456789)); Console.ReadLine(); } } /* This code example produces the following output: 123456789 squared = 15241578750190521 */
using System; using System.Reflection; using System.Reflection.Emit;
publicclassExample { // The following constructor and private field are used to // demonstrate a method bound to an object. privateint test; publicExample(int test) { this.test = test; }
// Declare delegates that can be used to execute the completed // SquareIt dynamic method. The OneParameter delegate can be // used to execute any method with one parameter and a return // value, or a method with two parameters and a return value // if the delegate is bound to an object. // 1,声明用于执行方法的委托类型。
privatedelegate TReturn OneParameter<TReturn, TParameter0> (TParameter0 p0); publicstaticvoidMain() { // Example 2: A dynamic method bound to an instance. // // Create an array that specifies the parameter types for a // dynamic method. If the delegate representing the method // is to be bound to an object, the first parameter must // match the type the delegate is bound to. In the following // code the bound instance is of the Example class. // 2,创建用于为动态方法指定参数类型的数组。 Type[] methodArgs2 = { typeof(Example), typeof(int) };
// Create a DynamicMethod. In this example the method has no // name. The return type of the method is int. The method // has access to the protected and private data of the // Example class. // 3,创建 DynamicMethod。 DynamicMethod multiplyHidden = new DynamicMethod( "", typeof(int), methodArgs2, typeof(Example));
// Emit the method body. In this example ILGenerator is used // to emit the MSIL. DynamicMethod has an associated type // DynamicILInfo that can be used in conjunction with // unmanaged code generators. // // The MSIL loads the first argument, which is an instance of // the Example class, and uses it to load the value of a // private instance field of type int. The second argument is // loaded, and the two numbers are multiplied. If the result // is larger than int, the value is truncated and the most // significant bits are discarded. The method returns, with // the return value on the stack. // 4,发出方法主体。 ILGenerator ilMH = multiplyHidden.GetILGenerator(); ilMH.Emit(OpCodes.Ldarg_0);
// Create a delegate that represents the dynamic method. // Creating the delegate completes the method, and any further // attempts to change the method � for example, by adding more // MSIL � are ignored. // // The following code binds the method to a new instance // of the Example class whose private test field is set to 42. // That is, each time the delegate is invoked the instance of // Example is passed to the first parameter of the method. // // The delegate OneParameter is used, because the first // parameter of the method receives the instance of Example. // When the delegate is invoked, only the second parameter is // required. // 5,通过调用 CreateDelegate(Type, Object) 方法重载创建表示动态方法的委托（在步骤 1 中声明）的实例。 OneParameter<int, int> invoke = (OneParameter<int, int>) multiplyHidden.CreateDelegate( typeof(OneParameter<int, int>), new Example(42) );
Console.WriteLine("3 * test = {0}", invoke(3)); Console.ReadLine(); } }
/* This code example produces the following output: 3 * test = 126 */