renumbering chapters >= 19

24-class-metaprog/metabunch/pre3.6/bunch.py

@@ -0,0 +1,41 @@
+import collections
+import warnings
+
+class MetaBunch(type):
+    def __prepare__(name, *bases, **kwargs):
+        return collections.OrderedDict()
+
+    def __new__(meta_cls, cls_name, bases, cls_dict):
+        def __init__(self, **kw):
+            for k in self.__defaults__:
+                setattr(self, k, self.__defaults__[k])
+            for k in kw:
+                setattr(self, k, kw[k])
+
+        def __repr__(self):
+            rep = ['{}={!r}'.format(k, getattr(self, k))
+                    for k in self.__defaults__
+                    if getattr(self, k) != self.__defaults__[k]
+                  ]
+            return '{}({})'.format(cls_name, ', '.join(rep))
+
+        new_dict = { '__slots__':[], 
+            '__defaults__':collections.OrderedDict(),
+            '__init__':__init__, '__repr__':__repr__, }
+
+        for k in cls_dict:
+            if k.startswith('__') and k.endswith('__'):
+                if k in new_dict:
+                    warnings.warn(
+                        "Can't set attr {!r} in bunch-class {!r}".
+                        format(k, cls_name))
+                else:
+                    new_dict[k] = cls_dict[k]
+            else:
+                new_dict['__slots__'].append(k)
+                new_dict['__defaults__'][k] = cls_dict[k]
+
+        return super().__new__(meta_cls, cls_name, bases, new_dict)
+
+class Bunch(metaclass=MetaBunch):
+    pass