How Do I: Run a class... Change at runtime?

Question

Hello:

I have the following lines to run a class for updated. I would like to change the name at runtime. Can someone tell me how?

ClassUpdateTest UpdateClass;
UpdateClass = new ClassUpdateTest(m_EventStopThread, m_EventThreadStopped, this);
UpdateClass.Run();

The "ClassUpdateTest"... I woulod like to change at run time. I have the value of it in a variable called textBoxUpdate.Text.

Gustavo · Answer

Hello: I have tried what has been suggested and its not working or I am doing something wrong. (99% Probably I am doing something wrong.). Can someone tell me or show me some sample code on how I can resolve this issue.

Gustavo · Answer

LOL: Need to read some documentation...LOL... OK, where is the documentation. This is what I did: I do have a: using System.Reflection; The code is: //object myDynamicClass = Assembly.CreateInstance(ClassNameTextBox.Text); object myDynamicClass = Assembly .CreateInstance(textBoxClassName.Text); The error is: An object reference is required for the non-static field, method, or property 'System.Reflection.Assembly.CreateInstance(string)'

Mahesh Chand · Answer

OK this is what you do. You need to read some documentation :). Let's say, you have a TextBox named ClassNameTextBox . To create an instance the class that is entered in the TextBox, this is what you do. object myDynamicClass = Assembly.CreateInstance( ClassNameTextBox.Text ); This code will create an object containing the instance of your class. Now you can type cast to your class and do whatever you want.

Gustavo · Answer

Sam: I looked at MSDN and could not find what I needed. Like I said before... there are so many articles in MSDN that its hard for me to find what I needed. I just want to call a Class with the name that is saved/stotred in a TextBox. Sounds simple...LOL... BUT, what do I k now.

Sam Hobbs · Answer

I really suspect that what you are trying to do is easier than you think, but I am not sure. If I am correct, then Mahesh has led you in the wrong direction. If I am wrong then Mahesh has probably helped you more than I can.

Gustavo · Answer

Mahesh: Ok, I will look at MSDN for my answer. Yes, Like you said, I want to get the class name from a TextBox. Hope I can find a good sample on MSDN. MSDN has a lot of good stuff but at times, its hard to find samples.

Mahesh Chand · Answer

Yes you're close. You need to use reflection and Assembly class found in System.Reflection namespace. Using this class, you can create instance of any class (class name from your TextBox in this case) at runtime. Using Assembly class members, you can also get methods, properties and other members information of your dynamic class and call them and do whatever you want to do with them. Search C# Corner and MSDN for Assembly class and learn about its members. Cheers!

Sam Hobbs · Answer

There is a difference between class definitions and instances of a class. We need to understand what the class instance is. Is the data to be saved in the form?

Gustavo · Answer

Sam: It was a typo... it was to be " I would like to do the same for a 'Class'." Here is some pseudo code of what I am trying to do: Class oClassToCall = ( Class )oAssembly.CreateInstance( SelectedClass .ToString()); oClassToCall(); The variable: " SelectedClass " can be selected from somewhere... its just a variable value. It will be the name of the class that I want to run. It like what I am doing with the Form ans would like to do it with a Class.

Sam Hobbs · Answer

I don't understand how " save for a 'Class' " is relevant to the form. If the data to be saved is in the form, then we are making progress communicating. If the data to be saved is in the form, then the solution is very different from what you are asking.

Gustavo · Answer

Sam: Maybe what I am asking is semi-impossible. Let me try to explain it a little different. When I want to run/open window with a variable name: I would do the following: Form oFormToOpen = ( Form )oAssembly.CreateInstance( "ICEPack." + NodeTag_0[0].ToString()); oFormToOpen.MdiParent = this ; oFormToOpen.Show(); The NodeTag_0[0].ToString()); is the variable string that has the form that I want to open. I would like to do the sa,me for a 'Class'. BTW: It took me a while to find out there was a posting. I am not being notified by email any more.

Gustavo · Answer

Sam: Maybe what I am asking is semi-impossible. Let me try to explain it a little different. When I want to run/open window with a variable name: I would do the following: Form oFormToOpen = ( Form )oAssembly.CreateInstance( "ICEPack." + NodeTag_0[0].ToString()); oFormToOpen.MdiParent = this ; oFormToOpen.Show(); The NodeTag_0[0].ToString()); is the variable string that has the form that I want to open. I would like to do the save for a 'Class'. BTW: It took me a while to find out there was a posting. I am not being notified by email any more.

Sam Hobbs · Answer

I am sorry, but no, that does not make things much clearer. Based on my understanding, a good solution would be to have a base class and have virtual functions that do specific things in each derived class. One thing that is not clear is if the data is stored in the same table in a database or somewhere else. If somewhere else, then it is not clear if the fields are the same for everything.

Gustavo · Answer

Sam: What I am trying to do is: I will have a bunch of classes that will do my updates. I would like to load a dataGridView with them and then when I click on the one I want, I want to run it. Is that a bit clearer? LOL.

Sam Hobbs · Answer

Can you clarify what it is that you need to accomplish by changing the class name? My initial response is that you can't do what you are trying to do, at least not easily. My guess is that there is an easier way to do what you need to do.

How Do I: Run a class... Change at runtime?

Answers (15)