Path: csiph.com!usenet.pasdenom.info!goblin2!goblin.stu.neva.ru!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
From: "Prasad, Ramit" <ramit.prasad@jpmorgan.com>
To: "python-list@python.org" <python-list@python.org>
Subject: RE: [python-list] python application file format
Thread-Topic: [python-list] python application file format
Thread-Index: AQHNm+bBRJQ3VHoSeEO2cs3jMnGtp5egNE9w
Date: Fri, 28 Sep 2012 20:34:25 +0000
References: <5062F9D6.2060402@abzinc.com>
In-Reply-To: <5062F9D6.2060402@abzinc.com>
Accept-Language: en-US
Content-Language: en-US
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Precedence: list
Newsgroups: comp.lang.python
Message-ID: <mailman.1582.1348864506.27098.python-list@python.org>
Lines: 32
NNTP-Posting-Host: 2001:888:2000:d::a6
Xref: csiph.com comp.lang.python:30427

Benjamin Jessup wrote:=0D=0A> Hello all,=0D=0A> =0D=0A> What do people reco=
mmend for a file format for a python desktop=0D=0A> application? Data is co=
mplex with 100s/1000s of class instances, which=0D=0A> reference each other=
=2E=0D=0A> =0D=0A> Write the file with struct module? (Rebuild object point=
ers, safe,=0D=0A> compact, portable, not expandable without reserved space)=
=0D=0A> =0D=0A> Use cPickle with a module/class whitelist? (Can't easily po=
rt, not=0D=0A> entirely safe, compact enough, expandable)=0D=0A> =0D=0A> Us=
e JSON or similar? (Rebuild object pointers, portable, expandable, size?)=
=0D=0A> =0D=0A> Any advice is greatly appreciated!=0D=0A=0D=0AI would think=
 your options are pickle, json or database (either sqlite or =0D=0Asomethin=
g like Postgres)=2E I am unfamiliar with the struct module so I =0D=0Acanno=
t comment on its applicability=2E=0D=0A=0D=0AI would guess that your data w=
ould be best saved by using a sqlite =0D=0Adatabase=2E Your biggest problem=
 might be how the different classes are =0D=0Areferencing each other=2E If =
you are using identifiers then any of these =0D=0Aoptions will probably wor=
k=2E If you are using aggregation then I know=0D=0Athat pickle will work (a=
t least for built-in types)=2E JSON will=0D=0Akeep the structure but duplic=
ate elements=2E=0D=0A=0D=0A=0D=0A>>> a =3D [ 1,2,3 ]=0D=0A>>> b =3D [ 'a', =
'b', 'c' ]=0D=0A>>> a=2Eappend( b )=0D=0A>>> e =3D [ a,b ]=0D=0A>>> s =3D j=
son=2Edumps( e ) =0D=0A>>> eret =3D json=2Eloads( s )=0D=0A>>> id(eret[0][3=
]), id(eret[1]) # Same result for json and simplejson=0D=0A(329443808, 3276=
77272) =0D=0A>>> eret[0][3]=2Eappend( 'o')=0D=0A>>> eret[0][3], eret[1]=0D=
=0A([u'a', u'b', u'c', 'o'], [u'a', u'b', u'c'])=0D=0A=0D=0ASo pickle will =
be your easiest option, but I am not sure how well it=0D=0Awill scale with =
a large number items=2E Using sqlite/db should scale well=0D=0Abut it will =
take you longer/more effort to create a system for converting =0D=0Ayour ob=
jects to and from the DB=2E=0D=0A=0D=0A=0D=0A=0D=0AThis email is confidenti=
al and subject to important disclaimers and=0D=0Aconditions including on of=
fers for the purchase or sale of=0D=0Asecurities, accuracy and completeness=
 of information, viruses,=0D=0Aconfidentiality, legal privilege, and legal =
entity disclaimers,=0D=0Aavailable at http://www=2Ejpmorgan=2Ecom/pages/dis=
closures/email=2E