avoiding file corruption

[Amir Michail]

Diez B. Roggisch wrote:
> Amir Michail schrieb:
> > Paolo Pantaleo wrote:
> >> 27 Aug 2006 00:44:33 -0700, Amir  Michail <amichail at gmail.com>:
> >>> Hi,
> >>>
> >>> Trying to open a file for writing that is already open for writing
> >>> should result in an exception.
> >>>
> >>> It's all too easy to accidentally open a shelve for writing twice and
> >>> this can lead to hard to track down database corruption errors.
> >>>
> >>> Amir
> >>>
> >>> --
> >>> http://mail.python.org/mailman/listinfo/python-list
> >>>
> >> Even if it could be strange, the OS usually allow you to open a file
> >> twice, that's up to the programmer to ensure the consistency of the
> >> operations.
> >>
> >> PAolo
> >>
> >
> > But if this is usually a serious bug, shouldn't an exception be raised?
>
> executing "rm -rf /" via subprocess is usually also a bad idea. So? No
> language can prevent you from doing such mistake. And there is no way to
> know if a file is opened twice - it might that you open the same file
> twice via e.g. a network share. No way to know that it is the same file.
>
> Diez

The scenario I have in mind is something like this:

def f():
  db=shelve.open('test.db', 'c')
  # do some stuff with db
  g()
  db.close()

def g():
  db=shelve.open('test.db', 'c')
  # do some stuff with db
  db.close()

I think it would be easy for python to check for this problem in
scenarios like this.

Amir