Tim Van Wassenhove

Today i wanted to experiment with System.CodeDom. This little program requests the user to input names for a namespace, class and method. It also asks the user to input the code that should go into the method body. Then it generates an assembly (test.dll) and creates a new appdomain in which the assembly is loaded… Finally it initializes an instance of the created class and calls the method…

static void Main(string[] args)
{
 string loopEnd = "";
 while (loopEnd != "X")
 {
  //string namespaceName = "MySpace";
  //string className = "MyClass";
  //string methodName = "MyMethod";
  //StringBuilder stringBuilder = new StringBuilder("System.Console.WriteLine(\"hihi\");");

  Console.Write("Enter namespace: ");
  string namespaceName = Console.ReadLine();
  Console.Write("Enter class: ");
  string className = Console.ReadLine();
  Console.Write("Enter method: ");
  string methodName = Console.ReadLine();

  StringBuilder stringBuilder = new StringBuilder();
  Console.WriteLine("Enter method body (X to stop)");
  string input = Console.ReadLine();
  while (input != "X")
  {
   stringBuilder.Append(input);
   input = Console.ReadLine();
  }

  CodeCompileUnit codeCompileUnit = new CodeCompileUnit();

  CodeAttributeDeclaration assemblyTitleAttribute = new CodeAttributeDeclaration("System.Reflection.AssemblyTitle");
  assemblyTitleAttribute.Arguments.Add(new CodeAttributeArgument(new CodePrimitiveExpression("A Generated Assembly")));
  codeCompileUnit.AssemblyCustomAttributes.Add(assemblyTitleAttribute);

  CodeTypeDeclaration codeTypeDeclaration = new CodeTypeDeclaration();
  codeTypeDeclaration.Name = className;
  codeTypeDeclaration.IsClass = true;
  codeTypeDeclaration.Attributes = MemberAttributes.Public;

  CodeMemberMethod codeMemberMethod = new CodeMemberMethod();
  codeMemberMethod.Name = methodName;
  codeMemberMethod.Attributes = MemberAttributes.Public;
  codeMemberMethod.ReturnType = new CodeTypeReference(typeof(void));
  codeMemberMethod.Statements.Add(new CodeSnippetStatement(stringBuilder.ToString()));

  codeTypeDeclaration.Members.Add(codeMemberMethod);

  CodeNamespace codeNamespace = new CodeNamespace(namespaceName);
  codeNamespace.Types.Add(codeTypeDeclaration);
  codeCompileUnit.Namespaces.Add(codeNamespace);

  CompilerParameters compilerParameters = new CompilerParameters();
  compilerParameters.OutputAssembly = "test.dll";
  compilerParameters.GenerateExecutable = false;
  compilerParameters.GenerateInMemory = false;

  CSharpCodeProvider cSharpCodeProvider = new CSharpCodeProvider();
  CompilerResults compilerResults = cSharpCodeProvider.CompileAssemblyFromDom(compilerParameters, codeCompileUnit);

  AppDomain appDomain = AppDomain.CreateDomain("new appdomain");
  Assembly assembly = appDomain.Load(compilerResults.CompiledAssembly.FullName);
  object instance = assembly.CreateInstance(namespaceName + "." + className);
  instance.GetType().InvokeMember(methodName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.InvokeMethod, null, instance, null);
  AppDomain.Unload(appDomain);

  Console.WriteLine("Enter X to end (enter something different to continue)");
  loopEnd = Console.ReadLine();
 }
}