I would say in that case, the Parent and Child shouldn't need to know about each other - some kind of handler in a different file should.
Although I guess that doesn't work in all cases, like defining foreign key relationships when using an orm (like sqlalchemy) for example. But in the orm case, the way to get around that is... lazy resolution :^)
Although I guess that doesn't work in all cases, like defining foreign key relationships when using an orm (like sqlalchemy) for example. But in the orm case, the way to get around that is... lazy resolution :^)