Should I use nested classes in this case?

Asked 2008-08-02T02:51:36.470

I am working on a collection of classes used for video playback and recording. I have one main class which acts like the public interface, with methods like play(), stop(), pause(), record() etc... Then I have workhorse classes that do the video decoding and video encoding.

I just learned about the existence of nested classes in C++, and I'm curious to know what programmers think about using them. I am a little wary and not really sure what the benefits/drawbacks are, but they seem (according to the book I'm reading) to be used in cases such as mine.

The book suggests that in a scenario like mine, a good solution would be to nest the workhorse classes inside the interface class, so there are no separate files for classes the client is not meant to use and to avoid any possible naming conflicts. I don't know about these justifications. Nested classes are a new concept to me. Just want to see what programmers think about the issue.

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2 Answers

Sometimes it's appropriate to hide the implementation classes from the user -- in these cases it's better to put them in an foo_internal.h than inside the public class definition. That way, readers of your foo.h will not see what you'd prefer they not be troubled with, but you can still write tests against each of the concrete implementations of your interface.

answered 2008-09-16T09:31:01.600

Another thing to keep in mind is whether you ever envision different implementations of your work functions (such as decoding and encoding). In that case, you would definitely want an abstract base class with different concrete classes which implement the functions. It would not really be appropriate to nest a separate subclass for each type of implementation.

answered 2008-09-23T19:07:55.030

Should I use nested classes in this case?

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