[Zope-dev] persistence
I'm a Zope and Python newbie and I'm trying to utilize Persistence, but I've seen two different ways: import ZODB from Persistence import Persistent vs. from Globals import Persistent Are these different? If so, which is "better"? Please don't ask me to define better. ;-) Thanks, // mark ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] persistence
On Thu, 28 Jun 2001, Mark McEahern wrote: > I'm a Zope and Python newbie and I'm trying to utilize Persistence, but I've > seen two different ways: > > import ZODB > from Persistence import Persistent > > vs. > > from Globals import Persistent > > Are these different? If so, which is "better"? Please don't ask me to > define better. ;-) If you're just using Zope, both are acceptable. If you are just using ZODB, use the first. -Michel ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] persistence
At 01:40 PM 6/28/01 -0700, Mark McEahern wrote: >I'm a Zope and Python newbie and I'm trying to utilize Persistence, but I've >seen two different ways: > > import ZODB > from Persistence import Persistent As Michel said, this is only for non-Zope use. In this case the 'import ZODB' statement does some funky stuff with the namespace. ;-) But I do not even attempt to understand that now. Next year maybe... If anyone knows about some nice documentation discussing/explaining this behavior, could you post the link? Regards, Stephan -- Stephan Richter CBU - Physics and Chemistry Student Web2k - Web Design/Development & Technical Project Management ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
[Zope-dev] persistence and lists
Hello, I´m working on a product which contains custom data in a list of multiple dictionaries. How can I save the list/dictionaries after changes? Persistence is enabled (and works for other types), and "_p_changed" is set, also get_transaction().commit() is called. A second problem is that multiple instances of the product reference the same list. So if I change the list of one of the instances the other changes, too. The list and dictionaries are stored in a class variable(in the product) and not global. Thanks, Arndt. ___ DV electric [EMAIL PROTECTED] http://www.dvelectric.com Fon 0221/2725782Fax 0221/2725783 Burgmauer 20, 50667 Köln ___ ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] persistence and lists
Sounds like you are trying to persist a class attribute value. This is not possible because instance are persistent, not classes. This is also the reason that the values change over all the instances. You are changing a mutable attribute of the class in place. I would suggest setting the value in the constructor of your objects, to make sure it is an instance attribute rather than a class attr. This: class foo: def __init__(self): self.alist = [] def append(self ,v) self.alist.append(v) # changes instance attr self._p_changed = 1 # will work Instead of: class foo: alist = [] def append(self ,v) self.alist.append(v) # changes class(!) attr self._p_changed = 1 # Will not work, the instance was not changed! hth, Casey On Wednesday 18 September 2002 03:27 pm, Arndt Droullier wrote: > Hello, > I´m working on a product which contains custom data in a list of multiple > dictionaries. > How can I save the list/dictionaries after changes? Persistence is enabled > (and works for other types), and "_p_changed" is set, also > get_transaction().commit() is called. > > A second problem is that multiple instances of the product reference the > same list. So if I change the list of one of the instances the other > changes, > too. > The list and dictionaries are stored in a class variable(in the product) > and not global. > > Thanks, Arndt. > > ___ > DV electric [EMAIL PROTECTED] http://www.dvelectric.com > Fon 0221/2725782Fax 0221/2725783 Burgmauer 20, 50667 Köln > ___ ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] persistence and lists
From: "Arndt Droullier" <[EMAIL PROTECTED]> > How can I save the list/dictionaries after changes? The easiest thing to do is to is to use PersistentMapping and PersistentList. Create them in __init__ with "self.dictionary = PersistentMapping()" instead of setting them as a class attribute. ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
[Zope-dev] Persistence Module Confustion (fwd)
I am trying to import the MailHost module that has dependencies with the Persistence package. The interpreter complains that it cannot load the Persistence modules and when I examine the package there is no content or modules. How can I fix my code to resolve these dependencies? Have the Persistence modules been deprecated? Thanks, ___ Zope-Dev maillist - [EMAIL PROTECTED] http://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://mail.zope.org/mailman/listinfo/zope-announce http://mail.zope.org/mailman/listinfo/zope )
[Zope-dev] Persistence ( was Thread Safe Counting )
>> Morten's product stores the counter's >> value in a file on the filesystem, and so it doesn't cause the >> Data.fs to grow. > >Hmmm, well, my counter above wouldn't cause the data.fs to grow all that much, >since it subclasses Persistent and so gets its own pickle jar. > >cheers, > >Chris So subclassing persistent will avoid changes to the object being stored and roll-backable in the ZODB? Nice! Now, if only we could get this sort of store-in-place functionality on a more fine-grained level (like on individual properties) - we could avoid a lot of coding to prevent ZODB bloat with simple features.. Ie, if I were to make a 'persistent porperty' on a DTML method, I could store counter information in that property without worry of ZODB bloat. Hrm... *Jon staes into the distance wondering how much will break if he tries to implement a 'persistent' flag for properties* ~Jon ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] Persistence Module Confustion (fwd)
D. Bickle wrote at 2004-2-11 11:16 -0800: >I am trying to import the MailHost module that has dependencies with the >Persistence package. The interpreter complains that it cannot load the >Persistence modules and when I examine the package there is no content or >modules. > >How can I fix my code to resolve these dependencies? The "Persistence" module is "filled" by an import of "ZODB". The documentation string in its "__init__.py" explains why this is so. -- Dieter ___ Zope-Dev maillist - [EMAIL PROTECTED] http://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://mail.zope.org/mailman/listinfo/zope-announce http://mail.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] Persistence ( was Thread Safe Counting )
Jon Franz wrote: > > So subclassing persistent will avoid changes to the object being stored and > roll-backable in the ZODB? NO! read the posting again... Subclassing from persistent is HOW you make things live in the ZODB. However, objects that subclass Persistent get their own pickle jar, and so only make the ZODB grow by the size of themselves and their attributes each time they change. In my counter's case, that's not a lot :-) > Now, if only we could get this sort of > store-in-place functionality on a more fine-grained level (like on > individual > properties) - we could avoid a lot of coding to prevent ZODB bloat with > simple > features.. Ie, if I were to make a 'persistent porperty' on a DTML method, > I could store counter information in that property without worry > of ZODB bloat. I wouldn't be surprised if something like this happens at some stage ;-) cheers, Chris ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
RE: [Zope-dev] Persistence ( was Thread Safe Counting )
Ah! this makes more sense, the idea of persistent properties even fits with this idea, though a true write-in-place property might be even better for some applications ;) Next time I'll read the whole thread and not the last post in it! > -Original Message- > From: Chris Withers [mailto:[EMAIL PROTECTED]] > Sent: Sunday, February 11, 2001 1:05 PM > To: Jon Franz > Cc: '[EMAIL PROTECTED]' > Subject: Re: [Zope-dev] Persistence ( was Thread Safe Counting ) > > > Jon Franz wrote: > > > > So subclassing persistent will avoid changes to the object > being stored and > > roll-backable in the ZODB? > > NO! read the posting again... Subclassing from persistent is > HOW you make things > live in the ZODB. However, objects that subclass Persistent > get their own pickle > jar, and so only make the ZODB grow by the size of themselves > and their > attributes each time they change. In my counter's case, > that's not a lot :-) > > > Now, if only we could get this sort of > > store-in-place functionality on a more fine-grained level (like on > > individual > > properties) - we could avoid a lot of coding to prevent > ZODB bloat with > > simple > > features.. Ie, if I were to make a 'persistent porperty' on > a DTML method, > > I could store counter information in that property without worry > > of ZODB bloat. > > I wouldn't be surprised if something like this happens at > some stage ;-) > > cheers, > > Chris > ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
RE: [Zope-dev] Persistence ( was Thread Safe Counting )
Jon Franz <[EMAIL PROTECTED]> wrote > Ah! this makes more sense, the idea of persistent properties even > fits with this idea, though a true write-in-place property might be > even better for some applications ;) Two things: * Don't count on storing the hit counter as a separate, "persistence aware" object (i.e., with its own pickle jar) to avoid bloating your Data.fs. Hit counters are by definition high volume, and the space overhead for managing undoable persistence is higher than you might think. * Write-in-place will never be supported by packable/undoable storages (logically impossible); some "packless" storages are already in play (maybe even near release), so the semantics you want may be (soon) readily available by mounting a separate storage. Tres. -- === Tres Seaver[EMAIL PROTECTED] Digital Creations "Zope Dealers" http://www.zope.org ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
