是否可以重载我不拥有的类的隐式或显式强制转换运算符？

Question

Pretty much all in the title. Is it possible to create a cast overload on a class that I don't own. For instance, if I were to create a wrapper for the NotifyIcon class (which is sealed), I can't actually use it with anything; I'd have to return an instance which kinda kills the ability to do a decorator. Is it possible to create a cast overload somewhere where I can basically return the private instance of NotifyIcon? Sounds wonky, but I think it'll achieve what I want.

Normally, I'd do something like:

public static implicit operator MyClass(SomeOtherClass input)
{
    // do things to come up with a MyClass
}

But this only works when the return type is MyClass. I'd like to do something simple like:

public class MyPsuedoDecoratorClass
{
    private NotifyIcon _icon;

    public MyPsuedoDecoratorClass(NotifyIcon icon)
    {
        _icon = icon;
    }

    // some decorated methods

    public static implicit operator NotifyIcon(MyPsuedoDecoratorClass input)
    {
        return _icon;
    }   
}

So that I can use it as an initialization wrapper.

Answer 1

You basically can't, but you can use NotifyIcon 's tag to store it's artificial derived object which is still elegant:

public static class NotifyIconExtesionMethods {
    public static MyClass As<T>( this NotifyIcon notifyIcon ) {
        return notifyIcon.Tag as T;
    }
}

class MyClass {
    private NotifyIcon notifyIcon;

    public MyClass( ) {
        notifyIcon = ...;
        ...
        notifyIcon.Tag = this;
    }
    public T As<T>( ) {
        return notifyIcon as T;
    }
}

//In some method:
var notifyIcon = new MyClass( ).As<NotifyIcon>( );
...
var myClass = notifyIcon.As<MyClass>( );