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I'm making a Model View View-Model (MVVM) application using Delphi XE6.

Since I'm using Pascal rather than C#, I need to manage destruction myself. I'm not sure how to handle form destruction.

My Form has an associated FormViewModel. The FormViewModel should be responsible for all the form's behaviour. I would expect this to include destruction. Also, when the Form is destroyed, so must the FormViewModel be destroyed. So it makes sense to handle these things together. The problem is I can't destroy the FormViewModel from a method within the FormViewModel, since this is being destroyed.

On the other hand, I can handle the job in another class, such as a Controller class. But then I have to get the Form to tell the Controller which FormViewModel instance to destroy. This would involve the Form knowing about the FormViewModel, which is not compliant with MVVM.

Have I misunderstood something about MVVM? Is there a way to do this in an unmanaged language without violating MVVM?

sav
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1 Answers1

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If your Form object holds a reference to its FormViewModel object, the FormViewModel object can be easily disposed in the destructor of the Form object.

Your notion that the Form object should know nothing about the FormViewModel object is misplaced (and impossible in MVVM). The FormViewModel object is always tightly-bound to the Form object; the whole point of having a FormViewModel object is to have a layer of abstraction you can tightly bind to, so that you can decouple from the business domain objects.

Robert Harvey
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