Good reasons NOT to place ViewModels in separate assembly?

Question

I\'m developing a project using the MVVM pattern in WPF.

One of the key benefits to MVVM is maintaining clear separation between business logic and presentation.

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Answer 1

The actual question is ... what are assembles for?

They are a way to separate logic making it unavailable to other code unless you add a reference, so in fact they are a way of hiding parts of code from other parts.

Given this purpose and the way you are using it I would say that you're doing it right.

Having said that I find much easier to verify that the Views do not have any code behind in code reviews and keep the views in the same assembly. Less projects = faster compile and load times.

Answer 2

I don't see any spcific issues with this approach besides the general pro/con for using few/many projects.

Answer 3

We use this kind of separation in all of our products because it helps us to see if any code violates against the UI - business logic separation.

Most times we do it the same way as you have suggested:

• Sample.Presentation.exe (Contains all the WPF stuff, thin assembly)

• Sample.Applications.dll (Is responsible to the application's workflow, here are all ViewModels)

• Sample.Domain.dll (Here are the business rules)

We don't have encountered any issues yet and I don't expect to see any problems in future.

Answer 4

2 weeks now with my Model & View Models in a dll, my xaml in an exe and no problems whatsoever.