On Feb 27, 6:47 pm, "Ziga Seilnacht" <[EMAIL PROTECTED]> wrote: > Andrew Felch wrote: > > Thanks for checking. I think I narrowed the problem down to > > inheritance. I inherit from list or some other container first: > > > class PointList( list, AutoReloader ): > > def PrintHi1(self): > > print "Hi2" > > > class MyPrintingClass( AutoReloader ): > > def PrintHi2(self): > > print "Hi2v2" > > > Automatic reloading works for MyPrintingClass but not for PointList. > > Any ideas? > > > -Andrew > > Ah yes, this is the problem of list.__new__ not calling the next > class in MRO. Try to switch the bases, so that AutoReloader's > __new__ method will be called first. > > Ziga- Hide quoted text - > > - Show quoted text -
So there is another bug crippling Python (see https://sourceforge.net/tracker/?func=detail&atid=105470&aid=628925&group_id=5470 ). Pickle and cPickle get confused after reloading, and won't let you dump the objects to file using protocol 2. The bug occurred for me when an instance of an AutoReloader class had a member not derived from AutoReloader (error text: "it's not the same object" ). The workaround is to use text mode, which I assume means not using protocol 2. After that, you can reload them in text mode, and then dump them using protocol 2. This is not so bad since you only do it when you were going to dump objects to file anyway, so it really only takes 3x as long on those occassions. The metaclass adaptation is still incredibly useful because it avoids having to do pickle dump- loads when you wouldn't otherwise have had to (approaching an infinite speedup in those cases, thanks Ziga! :-). Another caveat is that pickle dumping doesn't work if there is a pointer to a global function (that changes) that is a member of an instance of a class derived from AutoLoader. The error message has subtext: "it's not the same object ". That doesn't seem so bad to me, since you don't have to do that type of thing (function pointers) so much now that you can use classes! The best solution would be to make pickle protocol 2 have the same behavior as the text protocol (i.e. actually work in this case). Regarding the function pointers, anybody (Ziga :-) know why it is that pickle chokes so hard on this? Is there some adaptation of the metaclass or a less beautiful hack that could fix it? Thanks to those readers following me down the rabbit hole. Ziga's metaclass adaptation has saved Python in my mind, and these nits seem to be worth discussing. - Andrew Felch -- http://mail.python.org/mailman/listinfo/python-list
