Fix-up the enumerate type example and move it to the end.

This commit is contained in:
Raymond Hettinger 2008-05-08 07:23:30 +00:00
parent cf98f03a62
commit 5a9fed75bd
1 changed files with 9 additions and 10 deletions

View File

@ -570,16 +570,6 @@ by the :mod:`csv` or :mod:`sqlite3` modules::
for emp in map(EmployeeRecord._make, cursor.fetchall()):
print emp.name, emp.title
Named tuples can also be used to generate enumerated constants:
.. testcode::
def enum(*names):
return namedtuple('Enum', ' '.join(names))(*range(len(names)))
Status = enum('open', 'pending', 'closed')
assert (0, 1, 2) == (Status.open, Status.pending, Status.closed)
In addition to the methods inherited from tuples, named tuples support
three additional methods and one attribute. To prevent conflicts with
field names, the method and attribute names start with an underscore.
@ -674,6 +664,15 @@ customize a prototype instance:
>>> default_account = Account('<owner name>', 0.0, 0)
>>> johns_account = default_account._replace(owner='John')
Enumerated constants can be implemented with named tuples, but it is simpler
and more efficient to use a simple class declaration:
>>> Status = namedtuple('Status', 'open pending closed')._make(range(3))
>>> Status.open, Status.pending, Status.closed
(0, 1, 2)
>>> class Status:
... open, pending, closed = range(3)
.. rubric:: Footnotes
.. [#] For information on the double-star-operator see