class NamedTuple( tuple ):
def __new__( cls, names ):
return NamedTuple.Spawn( names )
def __getattr__( self, name ):
try:
return tuple.__getitem__( self, tuple.__getattribute__( self, '_names' )[name] )
except KeyError:
raise AttributeError, "object has no attribute named '%s'" % name
except AttributeError:
raise RuntimeError, "'NamedTuple' class cannot be used directly, use subclass generated by Spawn instead"
def __setattr__( self, name, value ):
raise TypeError, "'NamedTuple' object has only read-only attributes (assign to .%s)" % name
def Spawn( names ):
class __temp( NamedTuple ):
def __new__( cls, values ):
return tuple.__new__( cls, values )
__temp._names = dict( zip( names, range( len( names ) )))
return __temp
Spawn = staticmethod( Spawn )
if __name__ == '__main__':
# There are two ways to Spawn a tuple class:
Employee = NamedTuple.Spawn(['first', 'last', 'id'])
Product = NamedTuple(['name', 'cost', 'profit', 'qty'])
emp1 = Employee(['Jane', 'Foo', 1])
# The number of values is not limited to the number of
# named attributes defined.
emp2 = Employee(['John', 'Bar', 2, 'What about this?'])
print emp1, emp1.last, emp1[2]
print emp2, emp2.first, emp2[3]
pro1 = Product(['Box', .10, .05, 100])
print pro1, pro1.profit, pro1[0]
