Design Patterns – OOP Way of Handling Flow Control Heavy Applications

control flowdesign-patternsobject-orientedobject-oriented-design

I'm refactoring a huge WPF application whose complexity stems from the way it deals with flow control. It has a lot of "tiny business rules" that make it really difficult to make a modification without breaking something. These rules are things like

If the window mode is foo but this is the first time they've pressed this button and the user has a certain role, show this, else validate another thing and show that, else show another thing.

I've thought about creating a lot of different classes for validation and keeping the global state but I'm not sure if there's a design pattern or something focused on dealing with this kind of situation.

Best Answer

One approach that might fit is a finite state machine. There are tools that help you build and visualize them but you can also model it with standard OOP practices.

Related Solutions

Dependency Injection – Abstract Factory Patterns in C#

It seems you're struggling trying to create objects that create objects... wouldn't you be better off just creating objects ?

Ninject allows you to do so in a very simple way :

// Ninject module
Bind<IRepository<SomeEntity>>().To<SomeEntityRepository>();

// injected class
public class SomeService
{
  public SomeService(IRepository<SomeEntity> repository)
  {
    // ...
  }
}

// get instance of injected class
var someService = kernel.Get<SomeService>();

I can't see the benefit of an abstract factory in addition to an IoC container when you're creating objects based on basic, compile-time-known constraints such as in your SomeViewFactory and SomeRepositoryFactory examples.

The dynamic nature of SomeFunctionalityFactory would be more debatable, but when you think of it, do you really need to instantiate an object with the built-in notion that it will never be able to be used by the current user ? Wouldn't it make more sense to have the object evaluate user authorization when the functionality is called ?

Best Answer

Related Solutions

Dependency Injection – Abstract Factory Patterns in C#

Related Topic