A private class that can be passed anywhere as a parameter - is such a thing possible?

I want to define a class, ClassA, that can be passed as a parameter to any method or class in a project (global scope). However, I want to enforce a constraint which will insure that ClassA can only be instantiated within the scope of a single ClassB. In other words, I want the class to have private scope with respect to ClassA while still being able to pass that object as a parameter to methods and classes distributed throughout the project.

I开发者_Python百科s this possible?

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You can make ClassA abstract, and make a concrete implementation private to ClassB (as a nested class).

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You can make ClassA a public abstract class, with an internal constructor.

ClassB can then define a class that derives from this, and creates the "real" instance. This will prevent anybody outside of your assembly from generating types of ClassA.

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If I'm understanding what you want to do here correctly.....

Make ClassB a nested class of ClassA and make the constructor for ClassA private.