Restrict custom attribute so that it can be applied only to Specific types in C#?

Question

I have a custom attribute which is applied to class properties and the class itself. Now all the classes that must apply my custom attribute are derived from a single base c

Answer 1

I'm not aware of any way to do this with custom attributes.
A better way would be to get the classes to implement an interface with a generic constraint

so

class MyAttribute
{
     // put whatever custom data you want in here
}

interface IAttributeService where T : MyBaseClass
{
     MyAttribute Value{get;}
}

then your base class would do this

class MyBaseClass : IAttributeService
{
     private MyAttribute m_attrib;

     IAttributeService.Value
     {
         get {return m_attrib;}
     }
}

That way the compiler will enforce the constraint at compile time so that only classes
derived from MyBaseClass can implement the interface.
I made it fairly extensible by defining a MyAttribute class but you could of course just return a string or a bool if you needed something simpler

I also made the MyAttribute member private so that derived classes couldn't see it and change it but could make it protected and allow derived classes access if you wanted to.