c# - Why dependency properties in WPF has to be Static

Question

Why a dependency property has to be Static?

I have seen that it has been already asked in some post here, but I am not able to understand it properly.

It will be great if someone can help me understand with a small snippet too.

Answer 1

The magic here is, the declaration of DependencyProperty is static not its value (i.e the memory storage). The declaration that you add with static keyword is just the identifier(key) of the DependencyProperty for a particular DependencyObject. As same identifier/key can be used by all instances of the DependencyObject to identify the property value hence it makes sense to make it static.

On the other hand, when we set the value of DependancyProperty by calling the SetValue on DependancyObject instance, then each instance of DependancyObject on which the SetValue is called will store its local value of the Property. This is handled internally by the DependancyObject class which maintain sort of Dictionary which has the mapping between the DependancyProperty identifier and the local value.