Changes

Fix metaclass of a class after removing its traits

If you have a class using traits, its metaclass will be TraitedMetaclass. Now, if you remove its traits, its class should be Metaclass. The problem is that if you use #fillFor: it will not be the case.

The origin of the problem comes from the fact that #fillFor: will set the metaclass class to TraitedMetaclass and this will not be updated if you set the trait composition to be empty.

I provided a fix that is not so good in my opinion, but I'll try to change the way the class builder deals with metaclass class later to simplify this system and remove the need of this fix.

Finally I moved a test from shift class builder tests to traits tests since it uses a trait

Update the way to declare a metaclass class and fix some bugs in the metaclass class selected

Fix test

Remove unused var

Fix bug causing classes to lose their traits.

Imagine you have two traits T1 and T2. You also have a class C1 using T1 and a class C2 subclassing C1 and using T2.
Now if you remove T1 from C1 a bug causes C2 to also lose its trait T2.

The bug comes from the fact that in the trait implementation we copy methods from TraitedMetaclass and TraitedClass in the class using traits. But only in the top most class. Thus, if we update the superclass and it does not have the traits methods anymore, then all subclasses also loses this API.

My proposed fix is to keep a flag to know if a class update makes it go from a TraitedMetaclass to another metaclass class and if this flag is true, we update the method dictionaries of the subclasses to get the methods from TraitedMetaclass and TraitedClass.

I added a test to check this

Add more tests