Is MVVM pointless? [closed]

Question

Is orthodox MVVM implementation pointless? I am creating a new application and I considered Windows Forms and WPF. I chose WPF because it's future-proof and offer lots of flexibility. There is less code and easier to make significant changes to your UI using XAML.

Since the choice for WPF is obvious, I figured that I may as well go all the way by using MVVM as my application architecture since it offers blendability, separation concerns and unit testability. Theoretically, it seems beautiful like the holy grail of UI programming. This brief adventure; however, has turned into a real headache. As expected in practice, I’m finding that I’ve traded one problem for another. I tend to be an obsessive programmer in that I want to do things the right way so that I can get the right results and possibly become a better programmer. The MVVM pattern just flunked my test on productivity and has just turned into a big yucky hack!

The clear case in point is adding support for a Modal dialog box. The correct way is to put up a dialog box and tie it to a view model. Getting this to work is difficult. In order to benefit from the MVVM pattern, you have to distribute code in several places throughout the layers of your application. You also have to use esoteric programming constructs like templates and lamba expressions. Stuff that makes you stare at the screen scratching your head. This makes maintenance and debugging a nightmare waiting to happen as I recently discovered. I had an about box working fine until I got an exception the second time I invoked it, saying that it couldn’t show the dialog box again once it is closed. I had to add an event handler for the close functionality to the dialog window, another one in the IDialogView implementation of it and finally another in the IDialogViewModel. I thought MVVM would save us from such extravagant hackery!

There are several folks out there with competing solutions to this problem and they are all hacks and don’t provide a clean, easily reusable, elegant solution. Most of the MVVM toolkits gloss over dialogs and when they do address them, they are just alert boxes that don’t require custom interfaces or view models.

I’m planning on giving up on the MVVM view pattern, at least its orthodox implementation of it. What do you think? Has it been worth the trouble for you if you had any? Am I just a incompetent programmer or does MVVM not what it's hyped up to be?

Answer 1

I deal with the dialogs issue by cheating. My MainWindow implements an IWindowServices interface that exposes all of the application-specific dialogs. My other ViewModels can then import the services interface (I use MEF, but you could easily just pass the interface through constructors manually) and use it to accomplish what is necessary. For instance, here is what the interface looks like for a little utility application of mine:

//Wrapper interface for dialog functionality to allow for mocking during tests
public interface IWindowServices
{
    bool ExecuteNewProject(NewProjectViewModel model);

    bool ExecuteImportSymbols(ImportSymbolsViewModel model);

    bool ExecuteOpenDialog(OpenFileDialog dialog);

    bool ExecuteSaveDialog(SaveFileDialog dialog);

    bool ExecuteWarningConfirmation(string text, string caption);

    void ExitApplication();
}

This puts all of the Dialog executions in one place and it can be easily stubbed out for unit testing. I follow the pattern that the client of the dialog has to create the appropriate ViewModel, which they can then configure as needed. The Execute call blocks and afterward the client can look at the contents of the ViewModel to see the Dialog results.

A more 'pure' MVVM design may be important for a large application, where you need cleaner insulation and more complex composition, but for small to medium sized apps, I think a practical approach, with appropriate services to expose required hooks, is quite sufficient.

Answer 2

Design patterns are there to help you, not hinder. A small part of being a good developer is knowing when to "break the rules". If MVVM is cumbersome for a task and you have determined the future value isn't worth the effort, then don't use the pattern. For example, as other posters have commented, why would you go through all the overhead to implement a simple about box?

Design patterns were never intended to be dogmatically followed.