Named tuples

[graham__fawcett at hotmail.com]

Oops, let's try that again:

|   class namedtuplewrapper(tuple):
|       """
|       wraps an existing tuple, providing names.
|       """
|
|       _names_ = []
|
|       def __getattr__(self, name):
|           try:
|               x = self._names_.index(name)
|           except ValueError:
|               raise AttributeError, 'no such field: %s' % name
|           if x >= 0:
|               return self[x]
|
|   class namedtuple(namedtuplewrapper):
|       """
|       Sugar for a class that constructs named tuples from
|       positional arguments.
|       """
|
|       def __new__(cls, *args):
|           return tuple.__new__(cls, args)
|
|
|   if __name__ == '__main__':
|
|       # namedtuple example
|
|       class foo(namedtuple):
|           _names_ = ['one', 'two', 'three', 'four', 'five']
|
|       f = foo(1, 2, 3, 4, 5)
|       assert f.one + f.four == f.five
|
|
|       # wrapper example
|
|       class loctime(namedtuplewrapper):
|           _names_ = [
|               'year', 'month', 'day',
|               'hour', 'min', 'sec',
|               'wday', 'yday', 'isdst'
|           ]
|
|       import time
|       print time.localtime()
|       loc = loctime(time.localtime())
|       print loc.year, loc.month, loc.day
|
|       # arbitrary naming...
|       loc._names_ = ['a', 'b', 'c']
|       print loc.a

-- Graham