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umount/remount
by Florent Guillaume 08 Mar '03

08 Mar '03

Is there any way to "unmount" then "remount" a mounted storage from a running Zope? Use case: mounting it read-only most of the time, and switching to read-write at selected points when updates are allowed. Florent -- Florent Guillaume, Nuxeo (Paris, France) +33 1 40 33 79 87 http://nuxeo.com mailto:fg@nuxeo.com

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implementing structured text alternative w/in Zope
by Toby Bologna 08 Mar '03

08 Mar '03

Hi, I'm a programmer but new to Zope. I'm developing a text markup language like Structured Text that better suits my needs outside the Zope/Python world. Would I be able to incorporate it within Zope, i.e., so I could edit the new format in the edit window and have it displayed as HTML by the server, handled as a Zope object, etc.? I'd like to do it as transparently as (on the lowest level) possible, but if it turns out I have to do it as a feature of a product, that will be OK. Any tips for either scenario much appreciated. Thanks in advance, --tb __________________________________________________ Do you Yahoo!? Yahoo! Tax Center - forms, calculators, tips, more http://taxes.yahoo.com/

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Re: [Zope-dev] Re: [Vote] PEP308 voting began
by Lennart Regebro 07 Mar '03

07 Mar '03

Steve Alexander wrote: > This is possible. But, the problem remains that both a and b (in your > example above) are evaluated. I don't see the problem with that, unless a or b actually do stuff, and modify stuff, and if it does, in ZPT it should then be put into a script, since the template itself shouldn't contain any business logic. I can see the use of a one-line if-else syntax in ZPT as a way to set an attribute without making a specific pythons script just for such a small piece of code, and this will do it. If you want to *DO* different stuff depending on a condition, that shouldn't be in the template. Also, Evan tells me that this already exists in python: expressions, and is called test(). So, problem solved, no additional uglyfication of Python is needed. :)

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ZODB: Are all handles closed?
by Ulla Theiss 07 Mar '03

07 Mar '03

Hello list, in our product (and additionally in an other process) we use separate ZODB-Storages. Opening and closing the ZODB several times the number of file-handles increases. We have separated the multiple openings and closings to the following code. It shows the increasing of the handles clearly. Have we forgotten to clear anything or made anything wrong? If not, has anybody an idea, how to fix or work around the problem. ----------------------------------snip------snap--------------------- from ZODB import FileStorage, DB for i in range (1,100): storage=FileStorage.FileStorage("TestZODB.fs") db = DB(storage) db.open() print "Open" db.close() print "Close" storage.close() ----------------------------------snip------snap--------------------- Enother nice behaviour we can achieve with the following code: ----------------------------------snip------snap--------------------- from ZODB import FileStorage, DB storage=FileStorage.FileStorage("TestZODB.fs") db = DB(storage) for i in range (1,100): db.open() print "Open" db.close() print "Close" storage.close() ----------------------------------snip------snap--------------------- It works about seven times. Then the programm hangs completely. Much thanks in advance, Ulla.

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R: DBTab and CMF
by Fabio Paracchini 06 Mar '03

06 Mar '03

Shane, I tried your suggestion and it worked seamlessly also on BDBStorage, you only have to copy the whole BDB directory and rename it. Thanks once again Fabio -----Messaggio originale----- Da: Shane Hathaway Inviato: mercoledi 5 marzo 2003 22.29 A: Fabio Paracchini Cc: zope-dev(a)zope.org Oggetto: Re: DBTab and CMF Fabio Paracchini wrote: > Hi Shane, > I was able to successfully install and use DBTab & BDBStorage, and > to > migrate a legacy archive of about 20Gb of Office documents. > > Now I run in this situation: I'd like to partition those archives, so that > everything is not in a single giant DB, but is split among several smaller > DBs. > > DBTab works perfectly if you have a 'standard' Zope environment, i.e. if you > have Mountpoints/Folders. > > I was not able to mount a different storage beneath a CMF Folder, it seems > that inside DBTab's code a mount point is derived from Folder, and that is > not shown in a CMF/Plone site. > > Do you have any clues about using DBTab's mount points in a CMF/Plone site ? Tres and I stumbled upon the right way to do this yesterday: you make a copy of your database first, then in the primary database you delete the items you want to load from the secondary database and replace them with mount points. A concrete example: Let's say for a moment that you have one big Data.fs and you want to move the folder at /Site/Documents to its own database. First make a copy of Data.fs called "Documents.fs". Set up dbtab.conf to open both databases and mount /Site/Documents from Documents.fs. When you restart Zope, initially nothing will have changed--the documents are still in the main database. Visit the folder at /Site and delete the Documents object. (If you have sufficient backups, this shouldn't make your heart race. ;-) ) Now add the DBTab mount point. /Site/Documents will come back, this time loading from Documents.fs. Rather than a Folder, the object at /Site/Documents will be whatever kind of object it used to be, whether it was a CMF PortalFolder or a Zazzywag Kanuliputz. Everything will work like it did before--you don't even need to restart a second time. You'll want to use DBTab 1.1, BTW--I think it solves all the former strange bugs, and it's significantly faster. You'll have to adapt for BDBStorage. > BTW is there a better way to ask you those questions, instead of mailing you > directly, and also make you and the Zope community happier ? I CC'ed zope-dev(a)zope.org. Shane - Disclaimer - This email and any attachments thereto may contain information which is confidential and/or protected by intellectual property rights and are intended for the sole use of the recipient(s) named above. Any use of the information contained herein (including, but not limited to, total or partial reproduction, communication or distribution in any form) or the taking of any action in reliance on the contents, by persons other than the designated recipient(s) is strictly prohibited. If you have received this email in error, please notify the sender either by telephone or by email and delete the material from any computer. Thank you for your cooperation.

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Re: Zope-Dev digest, Vol 1 #2021 - 13 msgs
by Tra^`n Tua^'n Vinh 06 Mar '03

06 Mar '03

----- Original Message ----- From: <zope-dev-request(a)zope.org> To: <zope-dev(a)zope.org> Sent: Thursday, March 06, 2003 12:00 AM Subject: Zope-Dev digest, Vol 1 #2021 - 13 msgs > Send Zope-Dev mailing list submissions to > zope-dev(a)zope.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://mail.zope.org/mailman/listinfo/zope-dev > or, via email, send a message with subject or body 'help' to > zope-dev-request(a)zope.org > > You can reach the person managing the list at > zope-dev-admin(a)zope.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Zope-Dev digest..." > > > Today's Topics: > > 1. Re: Declaring Dependencies for XML documents (Was: How > To Improve Cache Coherency for RAM/Disk Cache Manager...?) (Andy McKay) > 2. Re: Declaring Dependencies for XML documents (Was: HowTo > Improve Cache Coherency for RAM/Disk Cache Manager...?) (Shane Hathaway) > 3. Re: LOTS of roles? (Paul Winkler) > 4. [Vote] PEP308 voting began (Dieter Maurer) > 5. Re: Declaring Dependencies for XML documents (Was: HowTo Improve Cache Coherency for RAM/Disk Cache Manager...?) (Paul Winkler) > 6. Re: [Vote] PEP308 voting began (Guido van Rossum) > 7. Re: [Vote] PEP308 voting began (Matthew T. Kromer) > 8. Re: [Vote] PEP308 voting began (Evan Simpson) > 9. Re: Re: [Vote] PEP308 voting began (Paul Winkler) > 10. Re: [Vote] PEP308 voting began (Chris Withers) > 11. [Fwd: Re: [Zope-dev] [Vote] PEP308 voting began] (Chris Withers) > > --__--__-- > > Message: 1 > Date: Tue, 04 Mar 2003 10:59:03 -0800 > From: Andy McKay <andy(a)agmweb.ca> > To: Craeg K Strong <cstrong(a)arielpartners.com> > Cc: Jamie Heilman <jamie(a)audible.transient.net>, zope-dev(a)zope.org > Subject: Re: [Zope-dev] Declaring Dependencies for XML documents (Was: How > To Improve Cache Coherency for RAM/Disk Cache Manager...?) > > > Anyway, after talking this over with my colleague, I realize that > > the problem of *deriving* dependencies is fundamentally undecidable. > > We might be able to figure it out in the case of simple acquisition, > > like > > <span tal:replace="here/aObject/aMethod"/> > > But it is hopeless for pure python: > > > > <span > > tal:replace="python:I-can-do-anything-and-you-cant-stop-me(REQUEST)"/> > > :) > > Well you could, in theory, hook every object as CallProfiler does and > then you would know for each request what object was called and Cache > it. You could even do something really clever like using CallProfiler > automatically cache objects that took longer than a certain amount of > time... > > But there are more issues with that than there are days in a year and > you could be writing that code forever, letting the user figure it out > manually is an easier choice. > > Cheers. > -- > Andy McKay > > > > --__--__-- > > Message: 2 > Date: Tue, 04 Mar 2003 14:32:31 -0500 > From: Shane Hathaway <shane(a)zope.com> > To: Andy McKay <andy(a)agmweb.ca> > CC: Craeg K Strong <cstrong(a)arielpartners.com>, > Jamie Heilman <jamie(a)audible.transient.net>, zope-dev(a)zope.org > Subject: Re: [Zope-dev] Declaring Dependencies for XML documents (Was: HowTo > Improve Cache Coherency for RAM/Disk Cache Manager...?) > > Andy McKay wrote: > >> Anyway, after talking this over with my colleague, I realize that > >> the problem of *deriving* dependencies is fundamentally undecidable. > >> We might be able to figure it out in the case of simple acquisition, > >> like > >> <span tal:replace="here/aObject/aMethod"/> > >> But it is hopeless for pure python: > >> > >> <span > >> tal:replace="python:I-can-do-anything-and-you-cant-stop-me(REQUEST)"/> > >> :) > > > > > > Well you could, in theory, hook every object as CallProfiler does and > > then you would know for each request what object was called and Cache > > it. You could even do something really clever like using CallProfiler > > automatically cache objects that took longer than a certain amount of > > time... > > > > But there are more issues with that than there are days in a year and > > you could be writing that code forever, letting the user figure it out > > manually is an easier choice. > > Ah, but you might have something there. What if there were a cache > manager that simply dropped its contents whenever anything changes in > ZODB? You could associate nearly all scripts and templates with that > cache manager without any fear of stale cache entries. For many sites, > it could be an instant win. > > Shane > > > > --__--__-- > > Message: 3 > Date: Tue, 4 Mar 2003 14:28:17 -0500 > From: Paul Winkler <pw_lists(a)slinkp.com> > To: zope-dev(a)zope.org > Subject: Re: [Zope-dev] LOTS of roles? > > On Tue, Feb 25, 2003 at 06:33:16PM +0000, Florent Guillaume wrote: > > Leonardo Rochael Almeida <leo(a)hiper.com.br> wrote: > > > So I think you need dynamically calculated local roles. This can be > > > achieved by a user folder that returns a user object that overrides > > > ".getRolesInContext(object)" to take the location (or any other > > > attribute, such as an acquired "site") of "object" and check it against > > > your central authorization source (eg. LDAP). > > > > Note that you'll also want to change validate() if you go that route. > > It has a short-circuited version of getRolesInContext in it. > > I'm now looking into doing this... > and i haven't found what you mean. > there are a bunch of validates() in various modules in AccessControl, > which are you talking about? > > ]$ grep "def validate(" * 2> /dev/null > AuthEncoding.py: def validate(reference, attempt): > AuthEncoding.py: def validate(self, reference, attempt): > AuthEncoding.py: def validate(self, reference, attempt): > AuthEncoding.py: def validate(self, reference, attempt): > SecurityManager.py: def validate(self, accessed=None, container=None, name=None, value=None, > User.py: def validate(self, request, auth='', roles=_noroles): > User.py: def validate(self, request, auth='', roles=_noroles): > ZopeSecurityPolicy.py: def validate(self, accessed, container, name, value, context, > cAccessControl.c: /*| def validate(self, accessed, container, name, value, context > > > are you sure it's not BasicUser.allowed() that you mean? > there's a comment in there about checking roles manaully > rather than with getRolesInContext... > > -- > > Paul Winkler > http://www.slinkp.com > > > > --__--__-- > > Message: 4 > From: Dieter Maurer <dieter(a)handshake.de> > Date: Tue, 4 Mar 2003 20:21:18 +0100 > To: zope-dev(a)zope.org, zope(a)zope.org > Subject: [Zope-dev] [Vote] PEP308 voting began > > Attention: cross post > > PEP308 is concerned with the introduction of a ternary conditional > operator (something like an "if cond: val_true else: val_false") > into Zope. > > In my view, such an operator would make TALES expressions > easier because we could get rid of the "and/or" hack to > represent conditionals and we could forget about the "test" > function, which evaluates too eagerly. > > Please have a look at PEP308 and consider voting. > Details in "comp.lang.python.announce". > > > Dieter > > > --__--__-- > > Message: 5 > Date: Tue, 4 Mar 2003 15:11:11 -0500 > From: Paul Winkler <pw_lists(a)slinkp.com> > To: zope-dev(a)zope.org > Subject: Re: [Zope-dev] Declaring Dependencies for XML documents (Was: HowTo Improve Cache Coherency for RAM/Disk Cache Manager...?) > > On Tue, Mar 04, 2003 at 02:32:31PM -0500, Shane Hathaway wrote: > > Ah, but you might have something there. What if there were a cache > > manager that simply dropped its contents whenever anything changes in > > ZODB? You could associate nearly all scripts and templates with that > > cache manager without any fear of stale cache entries. For many sites, > > it could be an instant win. > > interesting idea. there's certainly plenty of sites, though, where > the cache would get invalidated so often that the cache would be > of limited value. e.g. a busy squishdot-type site, or many CMF sites. > and on those kind of sites, the busiest times are when you most need > the cacheing... > > but the simplicity is certainly appealing... and in my case, i > have a CMF site where this would likely be quite useful since > the public never logs in, only our content management team, and > we tend to make changes on dev servers and push them to production > in a big bunch. > > -- > > Paul Winkler > http://www.slinkp.com > > > > --__--__-- > > Message: 6 > To: Dieter Maurer <dieter(a)handshake.de> > cc: zope-dev(a)zope.org > Subject: Re: [Zope-dev] [Vote] PEP308 voting began > From: Guido van Rossum <guido(a)python.org> > Date: Tue, 04 Mar 2003 15:23:54 -0500 > > > Attention: cross post > > > > PEP308 is concerned with the introduction of a ternary conditional > > operator (something like an "if cond: val_true else: val_false") > > into Zope. > > > > In my view, such an operator would make TALES expressions > > easier because we could get rid of the "and/or" hack to > > represent conditionals and we could forget about the "test" > > function, which evaluates too eagerly. > > > > Please have a look at PEP308 and consider voting. > > Details in "comp.lang.python.announce". > > > > Dieter > > IMO TALES should solve this for itself by introducing an if/then/else > expression form rather than depending on Python. If you can have a > "not:.." expression, surely you can have an "if:..:then:..:else:.." > expression. > > --Guido van Rossum (home page: http://www.python.org/~guido/) > > > --__--__-- > > Message: 7 > Date: Tue, 04 Mar 2003 15:34:05 -0500 > From: "Matthew T. Kromer" <matt(a)zope.com> > To: zope-dev(a)zope.org > Subject: Re: [Zope-dev] [Vote] PEP308 voting began > > Guido van Rossum wrote: > > >IMO TALES should solve this for itself by introducing an if/then/else > >expression form rather than depending on Python. If you can have a > >"not:.." expression, surely you can have an "if:..:then:..:else:.." > >expression. > > > >--Guido van Rossum (home page: http://www.python.org/~guido/) > > > > > > Yes, I'd be interested in seeing some kind of expression superset > operator in TALES such that you could use some boolean logic in > expressions which had subexpressions of different types (ie path > expressions vs python expressions). Currently the "punt" is to go out > to Python for any logic other than the path expression OR syntax. > > e.g. > > tal:define="variable tales: path: path_component | string: foo" > > An inline if/else might be C like > > tal:define="variable tales: local_var ? path: path_componenta : > string: foo" > > where "tales:" is simply whatever the meta-expression handler name is. > > > > > --__--__-- > > Message: 8 > Date: Tue, 04 Mar 2003 15:21:57 -0600 > From: Evan Simpson <evan(a)4-am.com> > To: zope-dev(a)zope.org, zpt(a)zope.org > CC: Guido van Rossum <guido(a)python.org> > Subject: [Zope-dev] Re: [Vote] PEP308 voting began > > Guido van Rossum wrote: > > IMO TALES should solve this for itself by introducing an if/then/else > > expression form rather than depending on Python. If you can have a > > "not:.." expression, surely you can have an "if:..:then:..:else:.." > > expression. > > Now that you point it out, it's not even hard. Here's a > proof-of-concept, with really awful parsing (it obviously breaks on > nested if: then: else:), that actually works: > > class IfExpr: > def __init__(self, name, expr, compiler): > self._s = expr = expr.lstrip() > m = re.match('(.*) then:(.*) else:(.*)', expr) > if m is not None: > condexpr, thenexpr, elseexpr = m.groups() > self._cond = compiler.compile(condexpr) > self._then = compiler.compile(thenexpr) > self._else = compiler.compile(elseexpr) > > def __call__(self, econtext): > if econtext.evaluateBoolean(self._cond): > return econtext.evaluate(self._then) > return econtext.evaluate(self._else) > > (Tested with > <div tal:replace="if:options/x then:string:yes else:string:no">) > > Is this worth a robust implementation, ZPT folks? > > Cheers, > > Evan @ 4-am > > > > --__--__-- > > Message: 9 > Date: Tue, 4 Mar 2003 17:10:50 -0500 > From: Paul Winkler <pw_lists(a)slinkp.com> > To: zope-dev(a)zope.org > Subject: Re: [Zope-dev] Re: [Vote] PEP308 voting began > > On Tue, Mar 04, 2003 at 03:21:57PM -0600, Evan Simpson wrote: > > Is this worth a robust implementation, ZPT folks? > > maybe, but i'd rather first wait and see how the PEP goes. > it would suck to have to constantly deal with two totally > different flavors of ternary. > > -- > > Paul Winkler > http://www.slinkp.com > > > > --__--__-- > > Message: 10 > Date: Wed, 05 Mar 2003 12:53:33 +0000 > From: Chris Withers <chrisw(a)nipltd.com> > To: Guido van Rossum <guido(a)python.org> > CC: Dieter Maurer <dieter(a)handshake.de>, zope-dev(a)zope.org > Subject: Re: [Zope-dev] [Vote] PEP308 voting began > > Guido van Rossum wrote: > > > > IMO TALES should solve this for itself by introducing an if/then/else > > expression form rather than depending on Python. If you can have a > > "not:.." expression, surely you can have an "if:..:then:..:else:.." > > expression. > > I think not: is dubious and I'd find if-then-else way over the lines... > > Chris > > > > --__--__-- > > Message: 11 > Date: Wed, 05 Mar 2003 14:54:03 +0000 > From: Chris Withers <chrisw(a)nipltd.com> > To: zope-dev(a)zope.org > Subject: [Fwd: Re: [Zope-dev] [Vote] PEP308 voting began] > > I think this was for the list... > > Chris > > -------- Original Message -------- > Subject: Re: [Zope-dev] [Vote] PEP308 voting began > Date: Wed, 05 Mar 2003 08:42:10 -0500 > From: Brian Brinegar <brinegar(a)pier.ecn.purdue.edu> > To: Chris Withers <chrisw(a)nipltd.com> > References: <15972.64686.377126.329892(a)gargle.gargle.HOWL> > <200303042023.h24KNuH27603(a)odiug.zope.com> <3E65F34D.8020701(a)nipltd.com> > > Not sure if this applies, but lets say I have something like: > > <div tal:repeat="item container/myList"> > <div class="selectedItem" tal:condition="item/isCurrent">Item 1</div> > <div class="regularItem" tal:condition="not: item/isCurrent">Item 2</div> > </div> > > When this is viewed outside of TAL, say by a designer in Dreamweaver, > both styles are apparent and their presentation can be changed by the > designer. Where something like this: > > <div tal:repeat="item container/myList"> > <div class="selectedItem" tal:attributes="class ternary: > item/isCurrent: string: selectedItem | string: regularItem">Item</div> > </div> > > would not include both versions of the presentation when viewed outside > of TAL. I've always assumed any kind of if/else combo would break the > change design after implementation aspect of page templates. However a > little extra work for designers saves a ton of duplication for > developers, so I think we should go with it. I also agree that it should > be an addition to TAL rather than using whatever python ends up with. > That's my few cents. > > -Brian > > Chris Withers wrote: > > > Guido van Rossum wrote: > > > >> > >> IMO TALES should solve this for itself by introducing an if/then/else > >> expression form rather than depending on Python. If you can have a > >> "not:.." expression, surely you can have an "if:..:then:..:else:.." > >> expression. > > > > > > I think not: is dubious and I'd find if-then-else way over the lines... > > > > Chris > > > > > > _______________________________________________ > > Zope-Dev maillist - Zope-Dev(a)zope.org > > 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 maillist - Zope-Dev(a)zope.org > http://mail.zope.org/mailman/listinfo/zope-dev > > (To receive general Zope announcements, see: > http://mail.zope.org/mailman/listinfo/zope-announce > > For non-developer, user-level issues, > zope(a)zope.org, http://mail.zope.org/mailman/listinfo/zope ) > > End of Zope-Dev Digest > >

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Re: DBTab and CMF
by Shane Hathaway 05 Mar '03

05 Mar '03

Fabio Paracchini wrote: > Hi Shane, > I was able to successfully install and use DBTab & BDBStorage, and > to > migrate a legacy archive of about 20Gb of Office documents. > > Now I run in this situation: I'd like to partition those archives, so that > everything is not in a single giant DB, but is split among several smaller > DBs. > > DBTab works perfectly if you have a 'standard' Zope environment, i.e. if you > have Mountpoints/Folders. > > I was not able to mount a different storage beneath a CMF Folder, it seems > that inside DBTab's code a mount point is derived from Folder, and that is > not shown in a CMF/Plone site. > > Do you have any clues about using DBTab's mount points in a CMF/Plone site ? Tres and I stumbled upon the right way to do this yesterday: you make a copy of your database first, then in the primary database you delete the items you want to load from the secondary database and replace them with mount points. A concrete example: Let's say for a moment that you have one big Data.fs and you want to move the folder at /Site/Documents to its own database. First make a copy of Data.fs called "Documents.fs". Set up dbtab.conf to open both databases and mount /Site/Documents from Documents.fs. When you restart Zope, initially nothing will have changed--the documents are still in the main database. Visit the folder at /Site and delete the Documents object. (If you have sufficient backups, this shouldn't make your heart race. ;-) ) Now add the DBTab mount point. /Site/Documents will come back, this time loading from Documents.fs. Rather than a Folder, the object at /Site/Documents will be whatever kind of object it used to be, whether it was a CMF PortalFolder or a Zazzywag Kanuliputz. Everything will work like it did before--you don't even need to restart a second time. You'll want to use DBTab 1.1, BTW--I think it solves all the former strange bugs, and it's significantly faster. You'll have to adapt for BDBStorage. > BTW is there a better way to ask you those questions, instead of mailing you > directly, and also make you and the Zope community happier ? I CC'ed zope-dev(a)zope.org. Shane

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[Fwd: Re: [Zope-dev] [Vote] PEP308 voting began]
by Chris Withers 05 Mar '03

05 Mar '03

I think this was for the list... Chris -------- Original Message -------- Subject: Re: [Zope-dev] [Vote] PEP308 voting began Date: Wed, 05 Mar 2003 08:42:10 -0500 From: Brian Brinegar <brinegar(a)pier.ecn.purdue.edu> To: Chris Withers <chrisw(a)nipltd.com> References: <15972.64686.377126.329892(a)gargle.gargle.HOWL> <200303042023.h24KNuH27603(a)odiug.zope.com> <3E65F34D.8020701(a)nipltd.com> Not sure if this applies, but lets say I have something like: <div tal:repeat="item container/myList"> <div class="selectedItem" tal:condition="item/isCurrent">Item 1</div> <div class="regularItem" tal:condition="not: item/isCurrent">Item 2</div> </div> When this is viewed outside of TAL, say by a designer in Dreamweaver, both styles are apparent and their presentation can be changed by the designer. Where something like this: <div tal:repeat="item container/myList"> <div class="selectedItem" tal:attributes="class ternary: item/isCurrent: string: selectedItem | string: regularItem">Item</div> </div> would not include both versions of the presentation when viewed outside of TAL. I've always assumed any kind of if/else combo would break the change design after implementation aspect of page templates. However a little extra work for designers saves a ton of duplication for developers, so I think we should go with it. I also agree that it should be an addition to TAL rather than using whatever python ends up with. That's my few cents. -Brian Chris Withers wrote: > Guido van Rossum wrote: > >> >> IMO TALES should solve this for itself by introducing an if/then/else >> expression form rather than depending on Python. If you can have a >> "not:.." expression, surely you can have an "if:..:then:..:else:.." >> expression. > > > I think not: is dubious and I'd find if-then-else way over the lines... > > Chris > > > _______________________________________________ > Zope-Dev maillist - Zope-Dev(a)zope.org > 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 )

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How To Improve Cache Coherency for RAM/Disk Cache Manager...?
by Craeg K Strong 04 Mar '03

04 Mar '03

Hello: I am getting ready to release the next version of XMLTransform, and in revisiting the Caching strategy for the product, I realized there are larger issues that probably deserve a discussion here. The bottom line is that transforming XML to something else via XSLT is a potentially expensive operation, so that caching the results is often worthwhile. As I thought about the problem, I realized that this probably holds true for any sufficiently dynamic site where you employ caching because: - the cost of processing exceeds the cost of retrieval from cache by at least an order of magnitude - there are many more readers than writers Question: How can we ensure cache coherency? For example, you might have a ZPT that includes the results of several long-running PythonScripts, whose rendered result is cached. What happens when the code for those PythonScripts changes? Worse, what happens when the SQL data retrieved by the Z SQL Method that the PythonScripts operate on changes? Correct me if I am wrong, but today the Zope Cache Management facility takes into account changes in cached objects, but not objects on which they depend. One strategy for accounting for this problem is to invalidate objects in the cache based on a certain interval. That way objects are out of date for at most the length of the interval. This could be called the "pull" or reactive model. Alternatively, Cacheable objects might be somehow aware of the objects on which they depend, and invalidate themselves in the cache when one of their dependent objects changes. This could be called the "push" or proactive model. Depending on some parameters, they might even recalculate their results proactively so they could be re-cached immediately. Why make the unlucky user pay the price? The latter alternative is not infeasible. DTML and ZPT scripts must parse their contents in order to render, so the information is available somewhere. The question is: can/should this be addressed for Zope2? What about Zope3? Is one model more appropriate for a development setting (equal numbers of writers and readers) vs production (many more readers, few or no writers)? Any thoughts or sage advice on this topic would be much appreciated! Regards, --Craeg

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Trying to understand the nuances of a VerboseSecurity report ..
by Jean Jordaan 04 Mar '03

04 Mar '03

Hi all (and Shane in particular :) I'm triggering this error: Unauthorized: The owner of the executing script is defined outside the context of the object being accessed. Access to 'basic' of (License_PropertySheetsClass instance at e204528) denied. Access requires Access_contents_information_Permission, granted to the following roles: ['Administrator', 'Manager', 'Owner', 'Supporter']. The executing script is (PythonScript instance at e208eb8), owned by jean. I can't understand why .. there is exactly one acl_users in this Zope instance, in the root, where user 'jean' is defined. The whole application normally works fine. Currently, the error is being triggered by a ZUnit unit test. All the other unit tests (adding, editing and deleting instances of various kinds) works fine. The code where the error is occuring is this: """ # Create a new License instance and grab its propertysheet license_id = context.ObjectCounters.newID('License') new_license = container.newItem(license_id) new_license_propertysheet = new_license.propertysheets.basic """ All I can think is that that object 'basic' lacks context for some reason (i.e. lacks an acquisition wrapper?). I can't think why it lacks context .. we use that idiom all over the app, and don't normally get any problems. I'm trying to see if reading VerboseSecurity's source will help, but all I've found so far is a suspect double negation: """ def userHasRolesButNotInContext(user, object, object_roles): '''Returns 1 if the user has any of the listed roles but is not defined in a context which is not an ancestor of object. ''' """ Surely either one of those 'not's should go? -- Jean Jordaan http://www.upfrontsystems.co.za

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