So I have an abstract base class in a DLL and child classes of that class. I want the childs to be public, but the base to be private so that it cannot be accessed outside of the dll.
How do I do that?
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3 Answers
36
You don't and you can't.
If you want to expose the class as public, the base-type must be public. One other option is to have a public interface, and only expose the type via the interface (presumably with a factory method somewhere for creating instances).
One final option is to encapsulate the base-class rather than inherit it.
Marc Gravell
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Or all the methods/properties on the base class to be protected? but the class itself to be public? – Liam Nov 07 '12 at 13:09
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@Liam that depends what you're trying to protect against; for example, if someone external can *subclass* it, they have access to those methods anyway. – Marc Gravell Nov 07 '12 at 13:10
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3@Liam yes, `internal` would prevent external people from getting easy access; of course, with reflection they can do most things anyway. – Marc Gravell Nov 07 '12 at 13:11
19
Make it public, make all constructors internal (if you're using the default constructor, add a parameterless constructor to override that).
Then while public and not sealed, it can't be sub-classed by external code.
Jon Hanna
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Just to clarify what I was saying in comments on @Marc Gravel's answer you could
public ChildClass : ParentClass
{
}
public ParentClass
{
internal void MethodIdontWantToExpose()
{
}
}
That said an interface is probably the best solution
Liam
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