diff options
Diffstat (limited to 'Lib/collections.py')
| -rw-r--r-- | Lib/collections.py | 40 |
1 files changed, 25 insertions, 15 deletions
diff --git a/Lib/collections.py b/Lib/collections.py index 8e9f6d6..70fa903 100644 --- a/Lib/collections.py +++ b/Lib/collections.py @@ -11,40 +11,50 @@ import _abcoll __all__ += _abcoll.__all__ -def NamedTuple(typename, s): +def NamedTuple(typename, s, verbose=False): """Returns a new subclass of tuple with named fields. >>> Point = NamedTuple('Point', 'x y') - >>> Point.__doc__ # docstring for the new class + >>> 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) + >>> 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 = p # unpacks just like a tuple >>> x, y (11, 22) - >>> p.x + p.y # fields also accessable by name + >>> p.x + p.y # fields also accessable by name 33 - >>> p # readable __repr__ with name=value style + >>> 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 = s.split() - if not ''.join([typename] + field_names).replace('_', '').isalnum(): + 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) + argtxt = repr(field_names).replace("'", "")[1:-1] # tuple repr without parens or quotes 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,)) + return tuple.__new__(cls, (%(argtxt)s)) def __repr__(self): return '%(typename)s(%(reprtxt)s)' %% self - ''' % locals() + def __replace__(self, field, value): + 'Return a new %(typename)s object replacing one field with a new value' + return %(typename)s(**dict(list(zip(%(field_names)r, self)) + [(field, value)])) \n''' % locals() for i, name in enumerate(field_names): - template += '\n %s = property(itemgetter(%d))\n' % (name, i) + template += ' %s = property(itemgetter(%d))\n' % (name, i) + if verbose: + print(template) m = dict(itemgetter=_itemgetter) exec(template, m) result = m[typename] @@ -57,9 +67,9 @@ def NamedTuple(typename, s): if __name__ == '__main__': - # verify that instances are pickable + # verify that instances can be pickled from pickle import loads, dumps - Point = NamedTuple('Point', 'x y') + Point = NamedTuple('Point', 'x, y', True) p = Point(x=10, y=20) assert p == loads(dumps(p)) |