Looking for example of Command pattern for UI [closed]

Question

I'm working on a WinForm .Net application with the basic UI that includes toolbar buttons, menu items and keystrokes that all initiate the same underlying code. Right now the event handlers for each of these call a common method to perform the function.

From what I've read this type of action could be handled by the Command design pattern with the additional benefit of automatically enabling/disabling or checking/unchecking the UI elements.

I've been searching the net for a good example project, but really haven't found one. Does anyone have a good example that can be shared?

Answer 1

Let's first make sure we know what the Command pattern is:

Command pattern encapsulates a request as an object and gives it a known public interface. Command Pattern ensures that every object receives its own commands and provides a decoupling between sender and receiver. A sender is an object that invokes an operation, and a receiver is an object that receives the request and acts on it.

Here's an example for you. There are many ways you can do this, but I am going to take an interface base approach to make the code more testable for you. I am not sure what language you prefer, but I am writing this in C#.

First, create an interface that describes a Command.

public interface ICommand
{
    void Execute();
}

Second, create command objects that will implement the command interface.

public class CutCommand : ICommand
{
    public void Execute()
    {
        // Put code you like to execute when the CutCommand.Execute method is called.
    }
}

Third, we need to setup our invoker or sender object.

public class TextOperations
{
    public void Invoke(ICommand command)
    {
        command.Execute();
    }
}

Fourth, create the client object that will use the invoker/sender object.

public class Client
{
    static void Main()
    {
        TextOperations textOperations = new TextOperations();
        textOperation.Invoke(new CutCommand());
    }
}

I hope you can take this example and put it into use for the application you are working on. If you would like more clarification, just let me know.