On Saturday, 29 September 2012 02:05:07 UTC+5:30, Prasad, Ramit wrote: > Benjamin Jessup wrote: > > > Hello all, > > > > > > What do people recommend for a file format for a python desktop > > > application? Data is complex with 100s/1000s of class instances, which > > > reference each other. > > > > > > Write the file with struct module? (Rebuild object pointers, safe, > > > compact, portable, not expandable without reserved space) > > > > > > Use cPickle with a module/class whitelist? (Can't easily port, not > > > entirely safe, compact enough, expandable) > > > > > > Use JSON or similar? (Rebuild object pointers, portable, expandable, size?) > > > > > > Any advice is greatly appreciated! > > > > I would think your options are pickle, json or database (either sqlite or > > something like Postgres). I am unfamiliar with the struct module so I > > cannot comment on its applicability. > > > > I would guess that your data would be best saved by using a sqlite > > database. Your biggest problem might be how the different classes are > > referencing each other. If you are using identifiers then any of these > > options will probably work. If you are using aggregation then I know > > that pickle will work (at least for built-in types). JSON will > > keep the structure but duplicate elements. > > > > > > >>> a = [ 1,2,3 ] > > >>> b = [ 'a', 'b', 'c' ] > > >>> a.append( b ) > > >>> e = [ a,b ] > > >>> s = json.dumps( e ) > > >>> eret = json.loads( s ) > > >>> id(eret[0][3]), id(eret[1]) # Same result for json and simplejson > > (329443808, 327677272) > > >>> eret[0][3].append( 'o') > > >>> eret[0][3], eret[1] > > ([u'a', u'b', u'c', 'o'], [u'a', u'b', u'c']) > > > > So pickle will be your easiest option, but I am not sure how well it > > will scale with a large number items. Using sqlite/db should scale well > > but it will take you longer/more effort to create a system for converting > > your objects to and from the DB. > > > > > > > > This email is confidential and subject to important disclaimers and > > conditions including on offers for the purchase or sale of > > securities, accuracy and completeness of information, viruses, > > confidentiality, legal privilege, and legal entity disclaimers, > > available at http://www.jpmorgan.com/pages/disclosures/email.
Guess I shouldn't read or rely your posts (virus'es could be in them) :-D -- http://mail.python.org/mailman/listinfo/python-list
