| __all__ = ['deque', 'defaultdict', 'NamedTuple'] |
| |
| from _collections import deque, defaultdict |
| from operator import itemgetter as _itemgetter |
| import sys as _sys |
| |
| def NamedTuple(typename, s): |
| """Returns a new subclass of tuple with named fields. |
| |
| >>> Point = NamedTuple('Point', 'x y') |
| >>> Point.__doc__ # docstring for the new class |
| 'Point(x, y)' |
| >>> p = Point(11, y=22) # instantiate with positional args or keywords |
| >>> p[0] + p[1] # works just like the tuple (11, 22) |
| 33 |
| >>> x, y = p # unpacks just like a tuple |
| >>> x, y |
| (11, 22) |
| >>> p.x + p.y # fields also accessable by name |
| 33 |
| >>> p # readable __repr__ with name=value style |
| Point(x=11, y=22) |
| >>> p.__replace__('x', 100) # __replace__() is like str.replace() but targets a named field |
| Point(x=100, y=22) |
| >>> d = dict(zip(p.__fields__, p)) # use __fields__ to make a dictionary |
| >>> d['x'] |
| 11 |
| |
| """ |
| |
| field_names = tuple(s.replace(',', ' ').split()) # names separated by spaces and/or commas |
| if not ''.join((typename,) + field_names).replace('_', '').isalnum(): |
| raise ValueError('Type names and field names can only contain alphanumeric characters and underscores') |
| argtxt = ', '.join(field_names) |
| reprtxt = ', '.join('%s=%%r' % name for name in field_names) |
| template = '''class %(typename)s(tuple): |
| '%(typename)s(%(argtxt)s)' |
| __slots__ = () |
| __fields__ = %(field_names)r |
| def __new__(cls, %(argtxt)s): |
| return tuple.__new__(cls, (%(argtxt)s,)) |
| def __repr__(self): |
| return '%(typename)s(%(reprtxt)s)' %% self |
| def __replace__(self, field, value): |
| 'Return a new %(typename)s object replacing one field with a new value' |
| return %(typename)s(**dict(zip(%(field_names)r, self) + [(field, value)])) |
| ''' % locals() |
| for i, name in enumerate(field_names): |
| template += '\n %s = property(itemgetter(%d))\n' % (name, i) |
| m = dict(itemgetter=_itemgetter) |
| exec template in m |
| result = m[typename] |
| if hasattr(_sys, '_getframe'): |
| result.__module__ = _sys._getframe(1).f_globals['__name__'] |
| return result |
| |
| |
| |
| |
| |
| |
| if __name__ == '__main__': |
| # verify that instances can be pickled |
| from cPickle import loads, dumps |
| Point = NamedTuple('Point', 'x, y') |
| p = Point(x=10, y=20) |
| assert p == loads(dumps(p)) |
| |
| import doctest |
| TestResults = NamedTuple('TestResults', 'failed attempted') |
| print TestResults(*doctest.testmod()) |