Examples for named tuple subclassing should include __slots__
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index c383943..b276ab0 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -513,23 +513,24 @@
a fixed-width print format::
>>> class Point(namedtuple('Point', 'x y')):
+ ... __slots__ = ()
... @property
... def hypot(self):
... return (self.x ** 2 + self.y ** 2) ** 0.5
... def __str__(self):
... return 'Point: x=%6.3f y=%6.3f hypot=%6.3f' % (self.x, self.y, self.hypot)
- >>> for p in Point(3,4), Point(14,5), Point(9./7,6):
+ >>> for p in Point(3, 4), Point(14, 5/7.):
... print p
Point: x= 3.000 y= 4.000 hypot= 5.000
- Point: x=14.000 y= 5.000 hypot=14.866
- Point: x= 1.286 y= 6.000 hypot= 6.136
+ Point: x=14.000 y= 0.714 hypot=14.018
Another use for subclassing is to replace performance critcal methods with
faster versions that bypass error-checking and that localize variable access::
class Point(namedtuple('Point', 'x y')):
+ __slots__ = ()
_make = classmethod(tuple.__new__)
def _replace(self, _map=map, **kwds):
return self._make(_map(kwds.get, ('x', 'y'), self))
diff --git a/Lib/collections.py b/Lib/collections.py
index a234b44..47b0397 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -118,17 +118,19 @@
# test and demonstrate ability to override methods
class Point(namedtuple('Point', 'x y')):
+ __slots__ = ()
@property
def hypot(self):
return (self.x ** 2 + self.y ** 2) ** 0.5
def __str__(self):
return 'Point: x=%6.3f y=%6.3f hypot=%6.3f' % (self.x, self.y, self.hypot)
- for p in Point(3,4), Point(14,5), Point(9./7,6):
+ for p in Point(3, 4), Point(14, 5/7.):
print p
class Point(namedtuple('Point', 'x y')):
'Point class with optimized _make() and _replace() without error-checking'
+ __slots__ = ()
_make = classmethod(tuple.__new__)
def _replace(self, _map=map, **kwds):
return self._make(_map(kwds.get, ('x', 'y'), self))