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courses/python_oop/meta/metaclass_4.py

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+'''
+Метод __prepare__ вызывается перед __new__
+Создает словарь пространства имен cls_dict
+'''
+
+
+
+class MyMeta(type):
+
+    @staticmethod
+    def __prepare__(name, bases, **kwargs):
+        print('MyMeta.__prepare__ called... with {kwargs}')
+        print()
+        kwargs['bonus_attr'] = 'hello'
+        return kwargs
+    
+        '''
+        print('name:', name)
+        print('base: ', bases)
+        print('kwargs: ', kwargs)
+        print()
+        return {'NAME': 'Billy', 'age': 33}
+        '''
+
+    def __new__(cls, name, bases, cls_dict, **kwargs):
+        print('MyMeta.__new__ called...')
+        print('cls: ', cls, type(cls))
+        print('name: ', name, type(name))
+        print('bases: ', bases, type(bases))
+        print('cls_dict: ', cls_dict, type(cls_dict))
+        print('kwargs: ', kwargs)
+        return super().__new__(cls, name, bases, cls_dict)
+    
+class MyClass(metaclass=MyMeta, arg1=10, arg2=15):
+    pass
+
+def test_1():
+    my_class = MyClass()
+
+
+
+class CustomDict(dict):
+    def __setitem__(self, key, value):
+        print(f'Setting {key} = {value} in custom dictionary')
+        super().__setitem__(key, value)
+
+    def __getitem__(self, key):
+        print(f'Getting {key} from custom dictionary')
+        return int(super().__getitem__(key))
+
+
+class MyMeta(type):
+    @staticmethod
+    def __prepare__(name, bases):
+        d = CustomDict()
+        d[1] = 100
+        d['a'] = 'b'
+        return d
+
+    def __new__(cls, name, bases, cls_dict):
+        print()
+        print('metaclass __new__ called...')
+        print(f'type(cls_dict) = {type(cls_dict)}')
+        print(f'cls_dict={cls_dict}')
+        return super().__new__(cls, name, bases, cls_dict)
+
+
+class MyClass(metaclass=MyMeta):
+    pass
+
+
+print(MyClass.__dict__)
+
+
+
+def main():
+    test_1()
+
+    
+if __name__ == '__main__':
+    main()