python namedtuple用法_python – 在namedtuple中使用’_’作为typename...

这是一个有点奇怪的例子.重点是为类及其属性提供有意义的名称.诸如__repr__和类docstring之类的一些功能从有意义的名称中获得了大部分好处.

FWIW,namedtuple工厂包括一个详细的选项,可以很容易地理解工厂对其输入做了什么.当verbose = True时,工厂打印出它创建的类定义：

>>> from collections import namedtuple

>>> example = namedtuple('_', ['NameOfClass1', 'NameOfClass2'], verbose=True)

class _(tuple):

'_(NameOfClass1, NameOfClass2)'

__slots__ = ()

_fields = ('NameOfClass1', 'NameOfClass2')

def __new__(_cls, NameOfClass1, NameOfClass2):

'Create new instance of _(NameOfClass1, NameOfClass2)'

return _tuple.__new__(_cls, (NameOfClass1, NameOfClass2))

@classmethod

def _make(cls, iterable, new=tuple.__new__, len=len):

'Make a new _ object from a sequence or iterable'

result = new(cls, iterable)

if len(result) != 2:

raise TypeError('Expected 2 arguments, got %d' % len(result))

return result

def __repr__(self):

'Return a nicely formatted representation string'

return '_(NameOfClass1=%r, NameOfClass2=%r)' % self

def _asdict(self):

'Return a new OrderedDict which maps field names to their values'

return OrderedDict(zip(self._fields, self))

def _replace(_self, **kwds):

'Return a new _ object replacing specified fields with new values'

result = _self._make(map(kwds.pop, ('NameOfClass1', 'NameOfClass2'), _self))

if kwds:

raise ValueError('Got unexpected field names: %r' % kwds.keys())

return result

def __getnewargs__(self):

'Return self as a plain tuple. Used by copy and pickle.'

return tuple(self)

NameOfClass1 = _property(_itemgetter(0), doc='Alias for field number 0')

NameOfClass2 = _property(_itemgetter(1), doc='Alias for field number 1')