2e reviewed manuscript

24-class-metaprog/checked/metaclass/checkedlib.py

@@ -78,7 +78,9 @@ class Field:
         self.storage_name = '_' + name  # <1>
         self.constructor = constructor
 
-    def __get__(self, instance, owner=None):  # <2>
+    def __get__(self, instance, owner=None):
+        if instance is None:  # <2>
+            return self
         return getattr(instance, self.storage_name)  # <3>
 
     def __set__(self, instance: Any, value: Any) -> None:

24-class-metaprog/factories.py

@@ -49,9 +49,8 @@ def record_factory(cls_name: str, field_names: FieldNames) -> type[tuple]:  # <2
             yield getattr(self, name)
 
     def __repr__(self):  # <6>
-        values = ', '.join(
-            '{}={!r}'.format(*i) for i in zip(self.__slots__, self)
-        )
+        values = ', '.join(f'{name}={value!r}'
+            for name, value in zip(self.__slots__, self))
         cls_name = self.__class__.__name__
         return f'{cls_name}({values})'
 

24-class-metaprog/metabunch/from3.6/bunch.py

@@ -28,7 +28,7 @@ Here are a few tests. ``bunch_test.py`` has a few more.
     >>> Point(x=1, y=2, z=3)
     Traceback (most recent call last):
       ...
-    AttributeError: 'Point' object has no attribute 'z'
+    AttributeError: No slots left for: 'z'
     >>> p = Point(x=21)
     >>> p.y = 42
     >>> p
@@ -51,7 +51,8 @@ class MetaBunch(type):  # <1>
             for name, default in defaults.items():  # <5>
                 setattr(self, name, kwargs.pop(name, default))
             if kwargs:  # <6>
-                setattr(self, *kwargs.popitem())
+                extra = ', '.join(kwargs)
+                raise AttributeError(f'No slots left for: {extra!r}')
 
         def __repr__(self):  # <7>
             rep = ', '.join(f'{name}={value!r}'

24-class-metaprog/metabunch/from3.6/bunch_test.py

@@ -26,7 +26,7 @@ def test_init():
 def test_init_wrong_argument():
     with pytest.raises(AttributeError) as exc:
         p = Point(x=1.2, y=3.4, flavor='coffee')
-    assert "no attribute 'flavor'" in str(exc.value)
+    assert 'flavor' in str(exc.value)
 
 
 def test_slots():

24-class-metaprog/timeslice.py

@@ -0,0 +1,91 @@
+
+"""
+Could this be valid Python?
+
+    if now >= T[4:20:PM]: chill()
+
+
+>>> t = T[4:20]
+>>> t
+T[4:20]
+>>> h, m, s = t
+>>> h, m, s
+(4, 20, 0)
+>>> t[11:59:AM]
+T[11:59:AM]
+>>> start = t[9:O1:PM]
+>>> start
+T[9:O1:PM]
+>>> start.h, start.m, start.s, start.pm
+(9, 1, 0, True)
+>>> now = T[7:O1:PM]
+>>> T[4:OO:PM]
+T[4:OO:PM]
+>>> now > T[4:20:PM]
+True
+"""
+
+import functools
+
+AM = -2
+PM = -1
+
+for n in range(10):
+    globals()[f'O{n}'] = n
+OO = 0
+
+@functools.total_ordering
+class T():
+
+    def __init__(self, arg):
+        if isinstance(arg, slice):
+            h = arg.start or 0
+            m = arg.stop or 0
+            s = arg.step or 0
+        else:
+            h, m, s = 0, 0, arg
+        if m in (AM, PM):
+            self.pm = m == PM
+            m = 0
+        elif s in (AM, PM):
+            self.pm = s == PM
+            s = 0
+        else:
+            self.pm = None
+        self.h, self.m, self.s = h, m, s
+
+    def __class_getitem__(cls, arg):
+        return cls(arg)
+
+    def __getitem__(self, arg):
+        return(type(self)(arg))
+
+    def __repr__(self):
+        h, m, s = self.h, self.m, self.s or None
+        if m == 0:
+            m = f'OO'
+        elif m < 10:
+            m = f'O{m}'
+        s = '' if s is None else s
+        if self.pm is None:
+            pm = ''
+        else:
+            pm = ':' + ('AM', 'PM')[self.pm]
+        return f'T[{h}:{m}{s}{pm}]'
+
+    def __iter__(self):
+        yield from (self.h, self.m, self.s)
+
+    def __eq__(self, other):
+        return tuple(self) == tuple(other)
+
+    def __lt__(self, other):
+        return tuple(self) < tuple(other)
+
+    def __add__(self, other):
+        """
+        >>> T[11:O5:AM] + 15  # TODO: preserve pm field
+        T[11:20]
+        """
+        if isinstance(other, int):
+            return self[self.h:self.m + other:self.pm]