Question

I have an application which spawns a lot of child objects and each of them works with some global application objects e.g. registers itself in the global application registry, updates application statistics etc.

How should application transfer the ability to access those global objects to the children? Should every child inherit from static CRegistry and CStatistics or should application pass Registry and Statistics to child at the moment of creation?

Thanks.

Answer 1

It would seem very odd to inherit from CRegistry – the child objects aren’t just specialized registries, are they? Their interaction with the registry is just to register themselves and then be found within the registry, I’d imagine. Ditto statistics.

It certainly sounds to me like the registry and statistics should just be passed in as appropriate (e.g. into the constructor). You may well not even need to keep the registry as a member variable, if the object just needs to register and then be found later.

If this really is a single, global registry then it might be a good time to use the singleton pattern – although that tends to make testing harder, in my experience.

Alternatively, could whatever’s creating the objects register them? Should it really be the child object’s job?