Partially Overriding a Virtual Auto-Property in a Child Class?

Question

Time for a theoretical question I just ran across.The following code is valid and compiles: public class Parent { public virtual object TestProperty { get; set; } } public class Child : Parent { private string _testValue = "Hello World!"; public override object TestProperty { get { return _testValue; } } } public class Consumer { Parent p = new Child(); public Consumer(){ p.TestProperty = 3; } }My question is: **Why does C# allow me to partially override the `TestProperty` auto property in a child when it leads to partially unpredictable behavior?** Is there a practical application?I'm allowed to set the value of TestProperty using the parent's setter (I checked the IL being generated and the setter is still setting the backing object in the parent class) even though value is not accessible to the public.

Answer 1

Yes, it is a bit silly this is allowed. As you've checked the CIL for it, I'm sure you're aware that properties are literally methods. You aren't partially overriding the property as much as you're only overriding the hidden "string TestProperty_get()" method while not overriding the hidden "void TestProperty_set(string value)" method. Property methods are no different from any other method in the runtime, and it's only by C#'s syntatic sugar do properties pretend to be variables.

As for practical application, yes. There may be scenarios where you only want or need to override only the getter or setter, such as adding an observer pattern to the setter while leaving the getter as-is.