Re: [Zope-dev] References, persistence, BTrees
At 05:49 PM 1/3/02 -0700, Jeffrey P Shell wrote: >'subscriber' is a reference to the subscribing object, and it's very >likely to be to an object in the ZODB. Is it wise to have more than one >persistent reference to a single persistent object? >I swear that I had once heard Jim say (vocally) that you could do >references like this in the ZODB now. I'm trying to avoid using Paths >because objects have a tendency to move around[*], and I have performance >concerns for a single event service object to have to call >'unrestrictedTraverse' to every subscriber. Unfortunately, you can't take this shortcut. Not because you can't store or retrieve references in this way, but because you can't get an acquisition context this way, which means security is shot, not to mention things like objects knowing their URLs. So although it's perfectly safe to point to objects in the ZODB from more than one place, it's almost always useless to do so with respect to an arbitrary Zope object. :( I don't know if this is changing in Z3, but I'm rather curious about the possibility, myself. ___ 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] References, persistence, BTrees
I'm experimenting with an event notification service based on a publish-subscribe model for some projects I'm working on. When a subscription comes in, a 'Subscription' object is made, that basically looks like this: class Subscription(Base): def __init__(self, subscriber, eventType, filter=None): self.subscriber = subscriber self.eventType = eventType self.filter = filter def __hash__(self): return hash(self.subscriber) & \ hash(self.eventType) & \ hash(self.filter) 'subscriber' is a reference to the subscribing object, and it's very likely to be to an object in the ZODB. Is it wise to have more than one persistent reference to a single persistent object? I swear that I had once heard Jim say (vocally) that you could do references like this in the ZODB now. I'm trying to avoid using Paths because objects have a tendency to move around[*], and I have performance concerns for a single event service object to have to call 'unrestrictedTraverse' to every subscriber. [*] (it's due to the annoyances with manage_beforeDelete() and friends that I'm writing this tool.) Second question: If I use the hash of the Subscription as a key, is there any advantages/disadvantages with using an IOBTree to hold Subscription objects instead of a PersistentMapping? Jeffrey P Shell, [EMAIL PROTECTED] ___ 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] Python Conference
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