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Re: shelve.open generates (22, 'Invalid argument') Os X 10.5 with Python 2.5

aahz

2/14/2010 6:21:00 PM

In article <7a9d26a8-0a9f-4bf3-bf50-0ac5e337f482@r24g2000yqd.googlegroups.com>,
seth <hklasky@gmail.com> wrote:
>
>We have a code that creates a simple Python shelve database. We are
>able to serialize objects and store them in the dbm file. This seem to
>work the same on Windows XP Python 2.5, Ubuntu 9.1 with Python 2.6,
>but on Os X 10.5 with Python 2.5 the database filename is changed by
>the operating system by attaching the .db extension to it. Does an one
>know why is that?

Nope -- any reason you can't change the filename?
--
Aahz (aahz@pythoncraft.com) <*> http://www.python...

"At Resolver we've found it useful to short-circuit any doubt and just
refer to comments in code as 'lies'. :-)"
1 Answer

seth

2/16/2010 10:04:00 PM

0

On Feb 14, 1:21 pm, a...@pythoncraft.com (Aahz) wrote:

> Nope -- any reason you can't change the filename?
> --

Os X 10.5 did not recognized the dbm extension.

But, I have been able to fix the problem (hope it helps somebody):
At http://docs.python.org/library/s... it says:

"shelve.open(filename[, flag='c'[, protocol=None[,
writeback=False]]])¶

Open a persistent dictionary. The filename specified is the base
filename for the underlying database. As a side-effect, an extension
may be added to the filename and more than one file may be created. By
default, the underlying database file is opened for reading and
writing. "

Then, I went ahead and try to find out which type of db file was being
created:

print whichdb.whichdb(dbmFile)#prints bsddb185
kpfmac:xLPR kpf$ python
Python 2.5.1 (r251:54863, Feb 9 2009, 18:49:36)
[GCC 4.0.1 (Apple Inc. build 5465)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import bsddb185
>>> bsddb185.open('realizations.db')
<bsddb.bsddb object at 0x12260>

I found that the dbm extension is generated by bsddb and bsddb3 so I
went ahead and installed it: sudo easy_install bsddb3.
Finally, in our code, I just went ahead and instead of using
shelve.open, I am calling shelve.BsdDbShelf(bsddb3.btopen(filename,
'c'))

#realizations=shelve.open( filename, 'c', 2, writeback =
False )
#hk 021010: need to use BsdDbShelf to ensure the usage of
bsddb3 on OsX 10.5
#shelve.open creates a bsddb185 file on OsX 10.5
#but shelve.open on OsX reads with bsddb3, who knows why...
#as a result the shelve.open throws
#<class 'bsddb.error'> (22, 'Invalid argument')
dbshelf=shelve.BsdDbShelf(bsddb3.btopen(filename, 'c'))
realizations=dbshelf

And that fixed on Os X 10.5. It also works fine on Windows, by
ensuring the proper import:
try:
import bsddb3
except:
import bsddb as bsddb3