I think the ability to read old files is essential. The ability to
write them is a mer nice-to-have.

On Fri, Nov 21, 2008 at 7:36 AM,  <skip@pobox.com> wrote:
>
>    me> ... I thought Guido was of the opinion that the 3.0 version should
>    me> be able to read dumb dbms written by earlier Python versions....
>
> And write them.  From msg72963:
>
>    (1) Be able to read databases written by Python 2.x.
>
>    (1a) Write databases readable by Python 2.x.
>
> Ah, but wait a minute.  I see your comment in msg76080:
>
>    If you look at the 2.7 code all it requires of keys and values in
>    __setitem__ is that they are strings; there is nothing about Latin-1 in
>    terms of specific encoding (must be a 3.0 addition to make the
>    str/unicode transition the easiest).
>
> The acid test.  I executed the attached mydb2write.py using Python 2.5 then
> executed the attached mydb3read.py using Python 3.0.  The output:
>
>    % python2.5 mydb2write.py
>    1 abc
>    2 [4, {4.2999999999999998: 12}]
>    3 <__main__.C instance at 0x34bb70>
>    % python3.0 mydb3read.py
>    1 b'abc'
>    2 [4, {4.2999999999999998: 12}]
>    Traceback (most recent call last):
>      File "mydb3read.py", line 13, in <module>
>        print(3, pickle.loads(db['3']))
>      File "/Users/skip/local/lib/python3.0/pickle.py", line 1329, in loads
>        return Unpickler(file, encoding=encoding, errors=errors).load()
>    _pickle.UnpicklingError: bad pickle data
>
> so if the ability to read Python 2.x dumbdbm files is still a requirement I
> think there's a little more work to do.
>
> cc'ing report@bugs.python.org to preserve the scripts with the ticket.
>
> Skip
>
>
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