Question

I am trying to figure out how does wpf manage static resources at the background. For example, if i get a static resource at the code behind and set it to null or define a new object for it, changes are not reflected. But if i get static resource and change a property of it, changes are reflacted. How does wpf understands if i changed a property or set object referance and behaves this way?

Thanks for your helps.

Answer 1

Actually, this is just the standard way how the objects behave in .NET. There is some object somewhere. You get a reference to an object, and if you set your local reference to null, any other object holding the reference will not notice that — after all, they have their own reference!

But if you change something that is “pointed to” by the reference, you change now the actual data, so everyone sees it!

Example:

class MyObject { public int i; }

MyObject ref1 = new MyObject() { i = 100 };
MyObject ref2 = ref1; // ref2 is just another reference to the object
ref1 = null;
Console.WriteLine(ref2.i); // prints 100, the object is still alive
ref1 = ref2;
ref1.i = 50;
Console.WriteLine(ref2.i); // prints 50, the object is changed

The same way it goes with static resources: you get a reference to the object, so if you null out your reference, others won’t mention it: they just have another reference.