Prothon, metaclasses, Zope [Was: A 'Python like' language]

[Roberto Lupi]

In article <95aa1afa.0403272243.78d60724 at posting.google.com>, 
> So, I reverted my mind to the pre-metaclass functioning mode (which required
> a certain effort) and I wrote a function that takes a class, looks at
> its dictionary, and raises an error if the class overrides an attribute
> which is already defined in the parent classes. The solution works,
> but it is kind of ugly compared to the metaclass solution:
> 
> 1. The metaclass can raise the error *before* the metaclass is created,
>    whereas the function works a posteriori, *after* the overriding is done;
>    if find it to be conceptually unsatisfactory, I don't want to create
>    a class just to throw it away. The alternative is to use a class factory,
>    but then I have just re-invented a metaclass with an ugly call syntax.

I would add the check to a test case for the class.

class XYZTestCase(ZopeTestCase):
	tested_class = XYZ

	def testOverriddenMethods(self):
		check_if_we_are_overriding_names_in(self.tested_class)

> 2. The metaclass can be inherited, so the check is automatic for all children;
>    on the contrary, I have to call the function by hand each time I define
>    a new class. This means writing twice the class name, which is error
>    prone if I later rename the class and I forget to update the function
>    call.

Test cases can be inherited.

class XYZ2TestCase(XYZTestCase):
	tested_class = XYZ2

-- 
Roberto Lupi