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Neaten-up the named tuple docs

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Raymond Hettinger 2008-01-10 23:00:01 +00:00
parent d08a8ebf2a
commit 15b5e55b48
2 changed files with 8 additions and 8 deletions
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14
Doc/library/collections.rst
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@ -364,8 +364,8 @@ they add the ability to access fields by name instead of position index.
method which lists the tuple contents in a ``name=value`` format. method which lists the tuple contents in a ``name=value`` format.
The *fieldnames* are a single string with each fieldname separated by whitespace The *fieldnames* are a single string with each fieldname separated by whitespace
and/or commas (for example 'x y' or 'x, y'). Alternatively, *fieldnames* and/or commas, for example ``'x y'`` or ``'x, y'``. Alternatively, *fieldnames*
can be a sequence of strings (such as ['x', 'y']). can be a sequence of strings such as ``['x', 'y']``.
Any valid Python identifier may be used for a fieldname except for names Any valid Python identifier may be used for a fieldname except for names
starting with an underscore. Valid identifiers consist of letters, digits, starting with an underscore. Valid identifiers consist of letters, digits,
@ -373,7 +373,7 @@ they add the ability to access fields by name instead of position index.
a :mod:`keyword` such as *class*, *for*, *return*, *global*, *pass*, *print*, a :mod:`keyword` such as *class*, *for*, *return*, *global*, *pass*, *print*,
or *raise*. or *raise*.
If *verbose* is true, will print the class definition. If *verbose* is true, the class definition is printed just before being built.
Named tuple instances do not have per-instance dictionaries, so they are Named tuple instances do not have per-instance dictionaries, so they are
lightweight and require no more memory than regular tuples. lightweight and require no more memory than regular tuples.
@ -518,16 +518,16 @@ a fixed-width print format::
... def hypot(self): ... def hypot(self):
... return (self.x ** 2 + self.y ** 2) ** 0.5 ... return (self.x ** 2 + self.y ** 2) ** 0.5
... def __str__(self): ... def __str__(self):
... return 'Point: x=%6.3f y=%6.3f hypot=%6.3f' % (self.x, self.y, self.hypot) ... 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, 5/7.): >>> for p in Point(3, 4), Point(14, 5/7.):
... print p ... print p
Point: x= 3.000 y= 4.000 hypot= 5.000 Point: x= 3.000 y= 4.000 hypot= 5.000
Point: x=14.000 y= 0.714 hypot=14.018 Point: x=14.000 y= 0.714 hypot=14.018
Another use for subclassing is to replace performance critcal methods with Another use for subclassing is to replace performance critcal methods with
faster versions that bypass error-checking and that localize variable access:: faster versions that bypass error-checking::
class Point(namedtuple('Point', 'x y')): class Point(namedtuple('Point', 'x y')):
__slots__ = () __slots__ = ()

2
Lib/collections.py
View file

@ -123,7 +123,7 @@ if __name__ == '__main__':
def hypot(self): def hypot(self):
return (self.x ** 2 + self.y ** 2) ** 0.5 return (self.x ** 2 + self.y ** 2) ** 0.5
def __str__(self): def __str__(self):
return 'Point: x=%6.3f y=%6.3f hypot=%6.3f' % (self.x, self.y, self.hypot) 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, 5/7.): for p in Point(3, 4), Point(14, 5/7.):
print p print p