Order Classes Automatically

[kwabenantim]

Summary

The order in which classes are added in package_info.yml is important. This order is propagated forward to the module wrappers. Base classes come before derived classes, a class should come before other classes that refer to it etc. When there are many classes in package_info.yml, figuring out an order that works can be hit or miss by trial and error, especially when adding a new class to an existing configuration that already contains many classes.

It would be a useful feature if cppwg could automatically work out the order to include classes in. Users could add classes to package_info.yml in any order without having to manually work out an order that won't break things. Classes could be added in alphabetical order, for instance, which would make it easier to find things when manually inspecting the configuration.

[kwabenantim]

When class registration is out of order, errors like this show up:

ImportError: arg(): could not convert default argument 
'foo_ptr: Foo*' in method '<class 'Bar'>.__init__' 
into a Python object (type not registered yet?)

This happens when Bar depends on Foo but Bar gets registered before Foo.