July 2000 - Zope-Dev

Re: [Zope-dev] Multi-homed objects?
by Chris Withers 17 Jul '00

17 Jul '00

Terry Kerr wrote: > > Where would the object aquire its attributes from? Would it try one of its > folders, then the other? Which order would it choose? Now that's a very good question ;-) Probably from the folder you referenced it from and then normal acquisition from then on... cheers, Chris

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Re: [Zope-dev] Errors causing half rendered pages
by Dieter Maurer 17 Jul '00

17 Jul '00

Chris Withers writes: > I'm still debugging and writing the navtree code I've mentioned before > and I've noticed that not infrequently, when rendering a page that > causes and error, I get a half rendered page rather than a nice Zope > error page. > > This is a bit waffly to put into the collector so I was wondering if > anyone else has had similar experiences? I saw this only when buggy HTML was generated. When I viewed the HTML source my Netscape browser sometimes showed me blinking parts that located the errors. Dieter

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RE: [Zope-dev] The Application object
by Chris McDonough 17 Jul '00

17 Jul '00

I'm not sure I understand. What is AppSingleton? What does the Instance() method do? > -----Original Message----- > From: Jeff K. Hoffman [mailto:jeff.hoffman@goingv.com] > Sent: Monday, July 17, 2000 11:54 AM > To: zope-dev(a)zope.org > Subject: [Zope-dev] The Application object > > > Hello, > > What is the easiest way for me to get ahold of the > Application object at > run-time? > > I am writing a Product that needs to access some things in the > Control_Panel, and need the app object to get there. > > I know how to do it given a reference to an object in the ZODB > (getPhysicalRoot(), etc.), but need a way to do it given no > references. I > need something like: > > import AppSingleton > > app = AppSingleton.Instance() > app.Control_Panel.blah > > --Jeff > > --- > Jeff K. Hoffman 704.849.0731 x108 > Chief Technology Officer > mailto:jeff.hoffman@goingv.com > Going Virtual, L.L.C. http://www.goingv.com/ > > > _______________________________________________ > Zope-Dev maillist - Zope-Dev(a)zope.org > 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 ) >

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Zope crashing on
by Steve Alexander 17 Jul '00

17 Jul '00

Zope 2.1.6 I'm using a "walk the tree" method of updating instances of a Python class, using an external method. Is there any reason that the following excerpt from an external method would cause Zope to crash shortly after it's been run on all suitable objects? The crash happens when I try to see one of the converted objects in my browser. def update_state(self): item = getattr(self, 'aq_base', self) item.content_state=PersistentMapping({'review':'public'}) item.review_state=ComputedAttribute(\ lambda self: self.content_state['review']) It seems to do something nasty to ZODB. I need to truncate Data.fs to get Zope working again. Perhaps I'm misunderstanding something about ComputedAttributes... -- Steve Alexander Software Engineer Cat-Box limited http://www.cat-box.net

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RE: [Zope-dev] The Application object
by Chris McDonough 17 Jul '00

17 Jul '00

How about a class attribute? class MyClass: myAttr2 = 'Default' def getMyAttr1(self): return self.myAttr1 def getMyAttr2(self): return self.myAttr2 If myAttr2 needs to be a ZClass instance, just grab it inside the class. > -----Original Message----- > From: Jeff K. Hoffman [mailto:jeff.hoffman@goingv.com] > Sent: Monday, July 17, 2000 2:44 PM > To: Chris McDonough > Cc: 'Jeff K. Hoffman'; Shane Hathaway; zope-dev(a)zope.org > Subject: RE: [Zope-dev] The Application object > > > On Mon, 17 Jul 2000, Chris McDonough wrote: > > > Jeff, what exactly do you need to do with setstate? can > you provide an > > example? > > I am simply trying to "upgrade" a persistent instance of a > Python class. > For instance: > > class MyClass: > > def __init__(self, id, title=''): > self.myAttr1 = 'Value 1' > > def getMyAttr1(self): > return self.myAttr1 > > Imagine that I use the class, as defined above, for a while, then > decide I need to modify it as follows: > > class MyClass: > > def __init__(self, id, title=''): > self.myAttr1 = 'Value 1' > self.myAttr2 = 'Value 2' > > def getMyAttr1(self): > return self.myAttr1 > > def getMyAttr2(self): > return self.myAttr2 > > I already have a few instances of MyClass in the ZODB, and > they only have > myAttr1; myAttr2 is not defined on existing instances, since > they will not > be constructed via the new __init__. Therefore, getMyAttr2() > will throw an > exception. > > The simple solution is to also define __setstate__: > > def __setstate__(self, state): > Persistent.__setstate__(self, state) > if not hasattr(self, 'myAttr2'): > self.myAttr2 = 'Value 2' > > Now, when the old instances of my object are de-ghosted from the ZODB, > __setstate__ notices that they don't have a myAttr2, and sets > it to the > value normally given by the constructor. > > Unfortunately, in my case, 'Value 2' is an instance of a ZClass. > Therefore, I need to get at Control_Panel. > > Hope this helps. Now I'm going to try Shane's wacky __of__ idea. :-) > > --Jeff > > --- > Jeff K. Hoffman 704.849.0731 x108 > Chief Technology Officer mailto:jeff.hoffman@goingv.com Going Virtual, L.L.C. http://www.goingv.com/

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RE: [Zope-dev] The Application object
by Chris McDonough 17 Jul '00

17 Jul '00

Jeff, what exactly do you need to do with setstate? can you provide an example? > -----Original Message----- > From: Jeff K. Hoffman [mailto:jeff.hoffman@goingv.com] > Sent: Monday, July 17, 2000 1:49 PM > To: Shane Hathaway > Cc: Jeff K. Hoffman; Chris McDonough; zope-dev(a)zope.org > Subject: Re: [Zope-dev] The Application object > > > On Mon, 17 Jul 2000, Shane Hathaway wrote: > > > "Jeff K. Hoffman" wrote: > > > > > Do I need to commit or abort even if I don't make changes to the > > > application object? The only thing I need it for is to get to the > > > Control_Panel; I am instantiating ZClass instances in the > constructor of a > > > Python class, i.e.: > > > > > > class MyClass: > > > > > > def __init__(self, id, title=''): > > > import Zope > > > app = Zope.app() > > > > > > ob = app.Control_Panel.Products.MyProduct.MyZClass('newId') > > > ob.id = 'newId' > > > > > > self._setObject('newId', ob) > > > > > > # Do I need a get_transaction().abort() here? Will > that not abort > > > # the wrong transaction? > > > > > > app._p_jar.close() > > > > > > > Hmm... you're creating an object in a separate connection > (I would call > > get_transaction().abort() just to be on the safe side...) > then copying > > that object over to the existing connection. This will > probably work, > > but I wouldn't be surprised to see thorny bugs appear. > > I have just hit one such thorny bug. Oh well. :-) > > > If you could instead get a handle to the existing > connection, you'd be > > following standard practice. You probably have a > manage_addMyClass() > > method, don't you? The "self" argument provided to that method is > > already connected to the database. self.getPhysicalRoot() will give > > you the equivalent of the app object. Then just change your > > constructor this way: > > > > > def __init__(self, app, id, title=''): > > > ob = app.Control_Panel.Products.MyProduct.MyZClass('newId') > > > ob.id = 'newId' > > > > > > self._setObject('newId', ob) > > Yeah, I was there, and that worked great. Then, I started > implementing my > __setstate__ method to "upgrade" old instances of my python > class. I need > to access the connection from here, too, and this is where the trouble > begins. > > AFAICT, I cannot call self.getPhysicalRoot() from > __setstate__, for the > same reason I can't call it from __init__. I can get by the __init__ > problem by passing app in as an argument from > manage_addMyProduct(). I can > find no such solution for __setstate__. > > > Best of luck! > > > > Shane > > All of my efforts are progressing towards one goal: How do I upgrade > existing instances of a ZClass? Since I could find no > __setstate__ method > for ZClasses, I re-wrote the containing class as a Python class and > figured I could leverage __setstate__ there, instantiating > the subordinate > ZClasses when required. > > No such luck. > > I am going to spend a little more time working on this. If I > can't find a > solution, I may drop ZClasses altogether and move all my code > to Python. I > had hoped not to do this, because my web guys can work with > ZClasses but > have no clue where to begin with a Python Product. > > I may just have to take total ownership of the code, as much > as I dislike > the idea, if I can find no other solution. > > --Jeff > > --- > Jeff K. Hoffman 704.849.0731 x108 > Chief Technology Officer mailto:jeff.hoffman@goingv.com Going Virtual, L.L.C. http://www.goingv.com/

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RE: [Zope-dev] The Application object
by Chris McDonough 17 Jul '00

17 Jul '00

So it's kosher then to reimport the Zope module and use app() in a constructor method, Shane? I was always afraid it would do something horrible. > -----Original Message----- > From: Jeff K. Hoffman [mailto:jeff.hoffman@goingv.com] > Sent: Monday, July 17, 2000 1:11 PM > To: Shane Hathaway > Cc: Chris McDonough; 'Jeff K. Hoffman'; zope-dev(a)zope.org > Subject: Re: [Zope-dev] The Application object > > > On Mon, 17 Jul 2000, Shane Hathaway wrote: > > > The way to get the root application object is to open a > connection to > > the ZODB and get the 'Application' object from the list of root > > objects. There is an easy shortcut: > > > > import Zope > > app = Zope.app() > > > > app now refers to a *copy* of the root Application object. > > Yeehaw, that worked! I was so close. :-) > > > When you're done modifying it and its descendants you have > to commit or > > abort the transaction. > > [snip] > > Do I need to commit or abort even if I don't make changes to the > application object? The only thing I need it for is to get to the > Control_Panel; I am instantiating ZClass instances in the > constructor of a > Python class, i.e.: > > class MyClass: > > def __init__(self, id, title=''): > import Zope > app = Zope.app() > > ob = app.Control_Panel.Products.MyProduct.MyZClass('newId') > ob.id = 'newId' > > self._setObject('newId', ob) > > # Do I need a get_transaction().abort() here? Will that > not abort > # the wrong transaction? > > app._p_jar.close() > > ... > > > This gives you all kinds of benefits like undo and elimination of > > threading conflicts. > > [snip] > > Good stuff. Thanks, Shane. > > > Shane > > --Jeff > > --- > Jeff K. Hoffman 704.849.0731 x108 > Chief Technology Officer mailto:jeff.hoffman@goingv.com Going Virtual, L.L.C. http://www.goingv.com/

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The Application object
by Jeff K. Hoffman 17 Jul '00

17 Jul '00

Hello, What is the easiest way for me to get ahold of the Application object at run-time? I am writing a Product that needs to access some things in the Control_Panel, and need the app object to get there. I know how to do it given a reference to an object in the ZODB (getPhysicalRoot(), etc.), but need a way to do it given no references. I need something like: import AppSingleton app = AppSingleton.Instance() app.Control_Panel.blah --Jeff --- Jeff K. Hoffman 704.849.0731 x108 Chief Technology Officer mailto:jeff.hoffman@goingv.com Going Virtual, L.L.C. http://www.goingv.com/

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2.2 annoying nit
by Martijn Faassen 17 Jul '00

17 Jul '00

Hi there, I see that the 2.2 still has this annoying, and seemingly completely unnecessary minor change in the tab order: Tabs for folder in 2.1: Contents View Properties Import/Export Security Undo Find Tabs for folder in 2.2: Contents Import/Export Properties View Find Security Undo Ownership What's the reason for this change? I'm rather used to the original configuration; I imagine other users are too. Why is everything reordered? I posted this to the collector 10 days ago, but the status is still 'pending' and 2.2 was released. While of course this is a minor thing, why make everyone relearn the interface? It's akin to switching 'file' and 'edit' around in a GUI. :) Regards, Martijn

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Multi-homed objects?
by Chris Withers 17 Jul '00

17 Jul '00

Is there any reason why an object cannot be contained in more than one Folder in the ZODB? Apparently what I'm talking about is very similar to hard linking in UNIX... I can't think of any reasons why this would be bad but I can't think how to implement an 'Add hard link to this object' function... Ideas/comments? cheers, Chris

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