Seconds to understand C # dynamically generate code from emit

You first need to declare an assembly name,

1//Specify a new assembly name2 var assemblyname = new AssemblyName ("Kitty");

Gets the assembly builder from the current application domain,

1//CREATE assembly builder2 var AssemblyBuilder = appdomain.currentdomain3   . DefineDynamicAssembly (AssemblyName, Assemblybuilderaccess.runandsave);

There are several dynamic assemblies that construct access restrictions:

• Assemblybuilderaccess.run; Indicates that an assembly can be executed, but cannot be saved.
• Assemblybuilderaccess.save; Indicates that the assembly can be saved, but cannot be executed.
• Assemblybuilderaccess.runandsave; Indicates that the assembly can be saved and can be executed.
• Assemblybuilderaccess.reflectiononly; Indicates that an assembly can only be used in a reflection context and cannot be executed.
• Assemblybuilderaccess.runandcollect; Indicates that the assembly can be unloaded and that the memory is recycled.

Constructs a dynamic module in an assembly,

1//Create module builder2 var ModuleBuilder = assemblybuilder.definedynamicmodule ("Kittymodule", "Kitty.exe");

A module is a collection of code that can have multiple modules in one assembly. And in theory, each module can be implemented in a different programming language, such as C#/VB.
Constructs a type constructor,

1//Create type builder for a class2 var typeBuilder = Modulebuilder.definetype ("Hellokittyclass", Typeattributes.public) ;

Define a method through the type constructor, get the method constructor, get the Il generator of the method constructor, and define the method functionality by writing IL code.

1//Create Method Builder 2 var MethodBuilder = Typebuilder.definemethod (3   "Sayhellomethod", 4   MethodAttributes . Public | Methodattributes.static, 5   null, 6   null); 7   8//Then get the method Il generator 9 var il = methodbuilder.get ILGenerator ();  /Then create the method Function12 il. Emit (Opcodes.ldstr, "Hello, kitty!"); -IL. Emit (Opcodes.call,   typeof (Console). GetMethod ("WriteLine", new type[] {typeof (String)})); Emit (Opcodes.call, typeof (Console). GetMethod ("ReadLine")); Emit (Opcodes.pop); We just read something here, throw it.17 il. Emit (Opcodes.ret);

Create types,

1/Then create the whole class type2 var hellokittyclasstype = TypeBuilder.CreateType ();

If the current assembly is operational, set a program entry,

1//Set entry point to this assembly2 assemblybuilder.setentrypoint (Hellokittyclasstype.getmethod ("Sayhellomethod")) ;

Save the dynamically generated assembly to a disk file.

1//Save Assembly2 Assemblybuilder.save ("Kitty.exe");

At this point, the Kitty.exe is deserialized into code with the Anti-compilation tool,

1 using System; 2  3 public class Hellokittyclass 4 {5 public   static void Sayhellomethod () 6   {7     Console.WriteLine ("Hello , kitty! "); 8     Console.ReadLine (); 9   }10}

Run the results,

Full code

 1 using System; 2 using System.Reflection; 3 using System.Reflection.Emit; 4 5 Namespace Emitintroduction 6 {7 Class program 8 {9 static void Main (string[] args) Ten {one//speci       FY a new assembly name12 var assemblyname = new AssemblyName ("Kitty");//CREATE Assembly BUILDER15 var AssemblyBuilder = Appdomain.currentdomain16.       DefineDynamicAssembly (AssemblyName, Assemblybuilderaccess.runandsave);//Create Module BUILDER20       var ModuleBuilder = assemblybuilder.definedynamicmodule ("Kittymodule", "Kitty.exe"); 23 24 Create type builder for a class25 var typeBuilder = Modulebuilder.definetype ("Helloki Ttyclass ", typeattributes.public);//Create method builder30 var MethodBuilder = Typebuilder.definemetho D ("Sayhellomethod", Methodattributes.public |     methodattributes.static,33 null,34 null); 35 36  Then get the method il generator37 var il = methodbuilder.getilgenerator (); and then create the Metho d function40 IL. Emit (Opcodes.ldstr, "Hello, kitty!"); A. Il. Emit (Opcodes.call, typeof (Console). GetMethod ("WriteLine", new type[] {typeof (String)})); Emit (Opcodes.call, typeof (Console). GetMethod ("ReadLine")); Emit (Opcodes.pop); We just read something here, throw it.47 il. Emit (Opcodes.ret);/Then create the whole class type50 var hellokittyclasstype = TypeBuilder.CreateType (); entry//Set assembly53 Assemblybuilder.setentrypoint (hellokittyclasstype.g Etmethod ("Sayhellomethod")), and/or save assembly57 assemblybuilder.save ("Kitty.exe"); Teline ("Hi, Dennis, a Kitty assembly have been generated for you."); Console.ReadLine (); 62}63}64}

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Further reading generating constructors and properties using emit

Seconds to understand C # dynamically generate code from emit