I agree completely - I was just pointing that it is possible. I think what people might not be aware of is that it's really an all or nothing proposition. You either jump in completely and pay the large cost to handle this in a maintainable, scalable way or don't do it at all. All of the "quick and easy" solutions have too many problems and aren't really maintainable.
Ted > -----Original Message----- > From: Eric Firing [mailto:[EMAIL PROTECTED] > Sent: Wednesday, September 17, 2008 12:01 PM > To: Ted Drain > Cc: matplotlib-users@lists.sourceforge.net > Subject: Re: [Matplotlib-users] save or pickle figure object > > Ted Drain wrote: > > We have some experience maintaining persistent object storage over > long > > periods of time. The best solution we've found is to do something > like > > this: > > > > - create a read/write method on each class. Every class that needs > to be > > stored must have this. This includes class you would store (eg > Figure) and > > things that are member variables of those classes. > > > > - Each class stores a version number along with it's data which > represents > > the version of the persistent representation for that class. So each > class > > has its own, internal versioning scheme that represents a specific > set of > > variables with specific types. > > > > - The read method on each class must check the version number and > then read > > the appropriate data for that version of itself. Whenever the > persistent > > representation of the class changes (usually if the member variables > > change), you increment the version number. Implicit in this is that > if you > > change the member variables of a class, the class read method must be > able > > to convert the variables that existed in the older version of itself > into > > the new member variables (since that's what the new methods on that > class > > will be using) > > > > FYI It is possible to use pickle to do this but you can't rely on > pickle to > > automatically save the member dictionary. You need to implement > > __getstate__ and __setstate__ and have them incorporate a version > number in > > the dictionary they return. In addition, you shouldn't blindly save > every > > member variable. If member variables can be constructed in terms of > other > > data, it may be better to store that data and then reconstruct the > member > > variables in the __setstate__ method. > > > > Using this type of system, you get a hierarchy of objects that each > have > > their own, internal versioning system. This lets you make changes to > a > > single class, increment it's version, and update its save/load > methods and > > it won't affect any other part of the system and still retains > backwards > > reading capability. > > > > Ted > > Sounds good--for some applications--but I would strongly oppose adding > this additional level of complexity to mpl. It's just not worth it. > If > you want to be able to work with a plot, then generate it with a > script, > and save the data and the script. That is the user's responsibility, > not mpl's. > > Unless mpl is taken over by a cadre of full-time professional > programmers, we have to try to keep it accessible to people who can > only > work on it sporadically. That means we need to try to keep it > simple--indeed, to work on simplifying it and cleaning up the rough > edges, and to work on maintaining a design that makes it easy to > improve > the real plotting capabilities and ease-of-use. > > Eric > > > > > >> -----Original Message----- > >> From: [EMAIL PROTECTED] > >> [mailto:[EMAIL PROTECTED] On Behalf Of > >> Eric Firing > >> Sent: Tuesday, September 16, 2008 7:04 PM > >> To: John Hunter > >> Cc: Josef Koller; matplotlib-users@lists.sourceforge.net > >> Subject: Re: [Matplotlib-users] save or pickle figure object > >> > >> John Hunter wrote: > >>> On Tue, Sep 16, 2008 at 5:06 PM, Josef Koller <[EMAIL PROTECTED]> > >> wrote: > >>>> Hi folks, > >>>> I would like to save preliminary figures for later processing and > >>>> refinement with matplotlib. Is there a way to save or pickle a > >> figure > >>>> object and later reload it. Matlab has a feature like that and and > I > >> was > >>>> wondering if matplotlib has it too. > >>> No, it doesn't exist. We've taken a stab at it once or twice, but > >>> have been stymied because we make extensive use of a python > extension > >>> libray CXX, and these objects have resisted our attempts to pickle > >>> them. With our recent transforms refactoring, which removes the > >>> hairiest CXX dependency, it may be worth taking another look, but > >>> noone is currently working on it. > >> My sense, based on very little experience, is that pickles of > >> complicated objects are very fragile, so even if we could pickle > >> figures, I fear it might cause more trouble ("I can't load this > >> absolutely critical figure I pickled 6 months ago") than it would be > >> worth. > >> > >> Eric > >> > >> -------------------------------------------------------------------- > --- > >> -- > >> This SF.Net email is sponsored by the Moblin Your Move Developer's > >> challenge > >> Build the coolest Linux based applications with Moblin SDK & win > great > >> prizes > >> Grand prize is a trip for two to an Open Source event anywhere in > the > >> world > >> http://moblin-contest.org/redirect.php?banner_id=100&url=/ > >> _______________________________________________ > >> Matplotlib-users mailing list > >> Matplotlib-users@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/matplotlib-users > >> Checked by AVG - http://www.avg.com > >> Version: 8.0.169 / Virus Database: 270.6.21/1674 - Release Date: > >> 9/16/2008 8:15 AM > > > > > > --------------------------------------------------------------------- > ---- > > This SF.Net email is sponsored by the Moblin Your Move Developer's > challenge > > Build the coolest Linux based applications with Moblin SDK & win > great prizes > > Grand prize is a trip for two to an Open Source event anywhere in the > world > > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > > _______________________________________________ > > Matplotlib-users mailing list > > Matplotlib-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/matplotlib-users ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
