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"""
The namedtuple class here is inspired from the namedtuple class
used in Python 2.6. Unfortunately, I cannot use that class,
since it does not work for field names which are Python keywords, and names
coming from a database are uncontrollable. There is still an issue
for names starting and ending with a double underscore, and for the
following names: _fields, _fromdict and _asdict.
Conflict with such names however is pretty rare and it is ignored.
"""
from operator import itemgetter
RESERVED_NAMES = set('_asdict _fields _fromdict'.split())
class Namedtuple(tuple):
_fields = ()
__slots__ = ()
@classmethod
def _fromdict(cls, dic):
return cls(dic[name] for name in self._fields)
def _asdict(self):
return dict(zip(self._fields, self))
def __repr__(self):
s = ', '.join('%r: %r' % (n, v) for (n, v) in zip(self._fields, self))
return '%s(%s)' % (self.__class__.__name__, s)
def namedtuple(typename, fields):
"Return a Namedtuple subclass without slots and with the right properties"
dic = dict(_fields=fields, __slots__=())
for i, f in enumerate(fields):
if f.startswith('__') and f.endswith('__') or f in RESERVED_NAMES:
raise NameError('%s is not a valid field name' % f)
dic[f] = property(
itemgetter(i), doc="Property for the field #%d, %r" % (i, f))
return type(typename, (Namedtuple,), dic)
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