Another Reflection Question

Another Reflection Question

• Florian_TT

  Hi,
  
  The classInstance.GetType() is just for you to see the type of the instance. Activator.CreateInstance is the actual method that creates the class instance. In the sample code, the class instance is stored as Object so you won't be able to invoke methods specific to a type (or class). You can cast classInstance to specific type and invoke its methods like:
  
  

  DirectCast(classInstance, MyClass).MyMethod()   ' This will invoke MyMethod method in MyClass class.

  
  
  On the other hand, if you know the method's name that you want to execute at runtime, you can also to something like this:
  
  

  assemblyType.InvokeMember("MyMethod", BindingFlags.InvokeMethod, Nothing, classInstance, New Object() {})   ' This will also invoke MyMethod method in MyClass class. Please refer to my previous post for reference.

  
  
  

• tomk_vsts_user

  Hi,
  So when this function is run will the NotificationDataObject come into existance and start doing what it does
  This is where I believe I am having a problem. I get to this point where I have the data but does not start the code running.
  
  Thanks
  Hoop
  

• Daniel Lord

  Hi,
  Below is what I am doing. Not sure how to get an instance of the class from the Activator::CreateInstance(prtrType).
  Should that line actually start the class
  
  Hoop
  
  
  
  

  void SearchPlugInDirectory( String *currentDirectory )< xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

        {

                                                              int indexStr = 0;

                                                              //For the dll Assemblies                                                                                     

                                                              Assembly *plugInAssemblies;

                                                              Type *ptrType;

                                                              Object *aModule;

                                                              String *moduleName;

                                                              MemberInfo *methodName;

                                                              String *methodType;

                                                              //Type* iFace = InputModule::IOModule;

                                                             

                                                                                                                         

           try

                                                   {

              String *fileName = S"";

   

                                                                                      // get list of files in current directory

              String *fileArray[] =  Directory::GetFiles( currentDirectory );

   

              // iterate through list of files

              for ( int dllFile = 0; dllFile < fileArray->Length; dllFile++ )

                                                                          {

                                                                                                  //Load dlls and types

                                                                                                  fileName = fileArray[ dllFile ];

                                                                                        plugInAssemblies = Assembly::LoadFrom(fileName);

                                                             

   

                                                                                                  Type* types __gc[] = plugInAssemblies->GetTypes();

                                                                                     

                                                                                       

                                                                                       MethodInfo* buildModuleMethod = plugInAssemblies->GetTypes() [0]->GetMethod(S"BaseModuleClass");

                                                                         

                                                                                                  ptrType = types[dllFile];

                                                                                                  moduleName = types[dllFile]->FullName; //the name

                                                                                                 

                                                                                                  aModule = Activator::CreateInstance(ptrType);

                                                                                                  aModule->GetType();

                                                                                                             

                                                                                                 

                                                                          } // end for

                                      

   

        } // end method SearchPlugInDirectory

  
  

• AkChauhan

  Hi,
  I guess this is where I am pretty much stumped. What to do with aModule. I cannot run anything with it, such as aModule->Build(); since the base app does not know that Build exists yet.
  Hoop
  

• Bar?? Soner U?akl?

  In your case, aModule is an instance of whatever ptrType happens to be and the instance is created by Activator::CreateInstance(ptrType).
  
  

• Infiniti

  You can use the Activator class to create class instances at runtime like this:
  
  

          Dim myAssembly As Assembly = Reflection.Assembly.LoadFrom("Assembly.dll")

          Try
              For Each assemblyType As Type In myAssembly.GetTypes()
                  If assemblyType.IsClass() AndAlso Not assemblyType.IsSealed() Then
                      Dim classInstance As Object = Activator.CreateInstance(assemblyType)
                      Debug.WriteLine(classInstance.GetType())
                  End If
              Next
          Catch ex As Exception
              Debug.WriteLine(ex.ToString())
          End Try
  
  Good Luck!

  
  
  

• mdegi

  Hi,
  I do have it that far in C++. I am stummped at the classInstance.GetType(), mine is actually, aModule->GetType();.
  Does not really do anything when it runs that line.
  Is that what is suppose to create the class instance
  
  Thanks
  Hoop
  

• GreyWolf

  An instance of a NotificationDataObject is created. The NotificationDataObject class is an ancestor class and this method creates an instance of one of its children. After it is run, the object is created and ready to be used. Methods can be called on it, properties can be accessed. There is no "start the code" point, as it is just instantiating an object.
  

• Michael Baarz

  To give you a C# example, with a different method of instantiation, here is what I've done in the past.
  
  

  private NotificationDataObject GetDataObject(string objectName) { Object[] args = new Object[] { }; Type t = Type.GetType("Notification.Data." + objectName + ", Notification.Data", true, true); object result = t.InvokeMember(objectName, System.Reflection.BindingFlags.CreateInstance, null, null, args); return (NotificationDataObject) result; }

  
  

• Andru

  Hi,
  I finnally got it. Took a cast,
  BaseModuleClass *plugin = dynamic_cast<BaseModuleClass *>(instance);
  pulgin->buildModule();
  
  Not sure if that is the best way but the dll did start running.
  
  Thanks For the direction
  Hoop
  
• Another Reflection Question