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Re: [Zope-dev] Functional programming
by Tres Seaver 24 Feb '00

24 Feb '00

Lalo Martins <lalo(a)hackandroll.org> asks: > To: zope-dev(a)zope.org > Subject: > > I know it probably is on the archives, but I didn't find it. > > Is there a good reason why I can't use map, filter and lambda > in DTML code? (They're not in the namespace.) Duncan Booth <duncan(a)rcp.co.uk> replies: > > lambda is available, but you have to specify an extra default > argument _vars=_vars > > Is there a good reason why I can't use map, filter and lambda > > in DTML code? (They're not in the namespace.) > > > Even without map and filter this can be useful on occasion if you > find yourself otherwise repeating an expression a lot of times. On > the other hand it isn't very pleasant to look at. > > I think the answer is probably that if you find you need to use map > and filter then you should consider using Python instead. Besides > you can get the effect of both of these with dtml-in. Lalo volleys: > > > > I think the answer is probably that if you find you need to use map > > and filter then you should consider using Python instead. > > Not really. Practical example: > > <dtml-in "map (Catalog.get_object, Catalog(...))"> > perform some operation, like listing the objects, without > need to bload the Catalog with all properties in the objects > </dtml-in> The downside here is that you activate every object found, which can be deadly for a really large result set. The rationale for using meta_data is to allow presentation of a limited view of the catalogued objects without pulling them into memory from the ZODB. > > And even if I _should_ use Python, then it should at least be > supported in PythonMethods. PythonMethods have no more access than DTML Methods/Documents (by design). > > > Besides you can get the effect of both of these with dtml-in. > > But the code you need for that looks mightly ugly, with > temporary variables, lots of REQUEST.set... let's not go there > :-) Agreed. filter() is particularly nice, as it eliminates the nesting of the <dtml-if> inside the <dtml-in>. For instance, to grab all contained objects which have a "browseable" property, set to true: <dtml-in "_.filter( lambda x: x.hasattr( 'browseable' ) and x.browseabe, objectValues() )"> ... </dtml-in> I will admit that I can't think of a particular use for map() offhand (but then, I'm not a lambda-head, either). -- ========================================================= Tres Seaver tseaver(a)palladion.com 713-523-6582 Palladion Software http://www.palladion.com

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RE: [Zope-dev] Folder Subclassing Problem
by James W. Howe 24 Feb '00

24 Feb '00

At 05:35 AM 2/24/00 -0500, Martijn Pieters wrote: >From: James W. Howe [mailto:jwh@allencreek.com] > >[Synopsis: > Created a subclass of Folder > Defined my own manage_main > Created instance of my folder subclass > Defined a new role for the folder and permitted the role to view > management screens, contents, but nothing else. > Tested for superuser and things worked. > Tested for my custom role and only saw the index_html] > >I still don't know for sure, as I don't have the time to investigate, >but I think there are some problems with the security interface, making >security too tight. It just doesn't work as expected. > >Try this: Create your Role and user in the top-level acl_users folder. >Then give that Role permission to view management screens either on the >top-level folder or on your own product. I tried what you suggested above, but the results were the same. I then decided to comment out the code in my subclass where I define my manage_main (i.e. manage_main = HTMLFile(...)). I reran my tests and this time both my superuser and my custom role were able to see the management interface and the contents screen (aka manage_main). For some reason, when my subclass uses its own manage_main, the permissions don't seem to work properly. Further evidence of this comes from some debugging I did in Management.py. I stepped through the filtered options code. When the "contents" object was asked for it's roles, it answered "Manager". Naturally, when the user wasn't the manager, this option got filtered out because the user didn't have access to it. In my security screen, I have View management screens, and Access contents information checked for both my manager and my custom role. I then modified my code to eliminate my definition of manage_main and instead use the one defined by ObjectManager. I then stepped through the debugger once again. This time, when the roles of the manage_main object were given, it came back as a collection of 'Manager', 'Publisher' (my new role), 'Manager'. I'm still investigating why this might be happening. James W. Howe mailto:jwh@allencreek.com Allen Creek Software, Inc. pgpkey: http://ic.net/~jwh/pgpkey.html Ann Arbor, MI 48103

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Scheduler Transactions (was Private Product Objects)
by Loren Stafford 24 Feb '00

24 Feb '00

Moving over to zope-dev... Martijn, don't worry. I'm not going to change designs in mid-stream. But I still have to think thru all the possibilities, perhaps covering ground that you've already explored and left behind. From: Martijn Pieters <mj(a)digicool.com> Sent: February 24, 2000 03:24 AM Subject: RE: [Zope] Private Product Objects (was: object icons) > (Events are called using ZClient, because the Events have to be called > independent of current web requests, and you do need a HTTP REQUEST > context). I assumed from the beginning that the event Dispatcher would fire events with RPC (ZClient or something like it) for the reasons you mention, plus the fact that the thread for the event is allocated by existing Zope mechanisms. Then I started thinking about transactions and atomicity. You don't want a system failure to result either in loss of an event or duplication of an event. But how can you ensure that in the case of the Scheduler? So, I started wondering how to atomically coordinate the updating of the Schedule catalog (to disarm the event) with the execution of the event's action method. I thought of having the Dispatcher wrap a transaction around the event's transaction, but that doesn't solve the problem. Transactions don't nest well. You could still have a failure between the end of the event's transaction and disarming of the event. I thought of using LPC (direct call) instead of RPC so that the Dispatcher could define the transaction in which the event runs and include the Schedule update in the same transaction. That sound great from the transaction point of view. But then the Dispatcher would have to manage threads for the events (not KISS), plus there would be no HTTP REQUEST context, etc. In short, I don't have a solution. Any ideas? -- Loren

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RE: [Zope-dev] Accessing root object
by Martijn Pieters 24 Feb '00

24 Feb '00

> From: Robert Sander [mailto:zope-dev@beteigeuze.cs.tu-berlin.de] > > On Thu, Feb 10, 2000 at 03:40:38PM -0000, Phil Harris wrote: > > I think there's something called app? > > > > It's declared in <zopedir>/lib/python/Main.py. > > > > That may be what your looking for?? > > I don't know, the object app is not in the global namespace > when __init__.py > of my Product is called. > > It may be the same problem with the discussed scheduler > product when creating > another thread, b ut I don't know. Here's what I'd do (in __init__.py): def initialize(context): app = context._ProductContext__app # Don't you love private name mangling if not hasattr(app, #IdForObject#): object = Object() app._setObject(#IdForObject#, object) get_transaction().note('Added Object') get_transaction().commit() context._ProductContext__app is the root object. #IdForObject# is a string ID for the object. -- Martijn Pieters, Software Engineer | Digital Creations http://www.digicool.com | Creators of Zope http://www.zope.org | mailto:mj@digicool.com ICQ: 4532236 | PGP: http://wwwkeys.nl.pgp.net:11371/pks/lookup?op=get&search=0xA8A32149 -------------------------------------------

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Functional programming
by Lalo Martins 24 Feb '00

24 Feb '00

I know it probably is on the archives, but I didn't find it. Is there a good reason why I can't use map, filter and lambda in DTML code? (They're not in the namespace.) []s, |alo +---- -- I am Lalo of deB-org. You will be freed. Resistance is futile. http://www.webcom.com/lalo mailto:lalo@webcom.com pgp key in the web page Debian GNU/Linux --- http://www.debian.org Brazil of Darkness -- http://zope.gf.com.br/BroDar

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Problems subclassing DTMLDocument and DTMLMethod
by Itamar Shtull-Trauring 24 Feb '00

24 Feb '00

I've decided to rewrite ZCache in an OO way, so I rewrote it and called it GenericCache. First thing I'm trying to make are cached DTMLDocument and DTMLMethod. GenericCache provides a Cache class that wraps all access to the object, and if the cache expires Cache reloads its data. How it reloads is determined by overloadng a _getData method in subclasses. So in a subclass of Cache and DTMLMethod _getData would call DTMLMethod.__call__, i.e. te cache would contain the rendered DTML. I subclass Cached DTMLDocument from Cache and DTMLDocument, Cached Method from Cache and DTMLMethod. I have two major problems: 1. The DTML only renders if I put all of it inside a <dtml-with "PARENTS[0]"></dtml-with>, otherwise it doesn't seem to acquire anything. Cache inherits from Acquisition.Implict and of course so does DTMLMethod - so why isn't acquisition working? 2. The Cached DTMLMethod behaves just like a DTMLDocument - possibley because of the above problem and/or my temporary solution. That is, it doesn't act as a method of the enclosing folder but as standalone object. I'd be very grateful if anybody could point me in the right direction - I put up the code at http://www.zope.org/Members/itamar/GenericCache -- The SNAFU Principle: True communication is possible only between equals Itamar S.T. itamars(a)ibm.net

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RE: [Zope-dev] Folder Subclassing Problem
by Martijn Pieters 24 Feb '00

24 Feb '00

From: James W. Howe [mailto:jwh@allencreek.com] <SNIP> > I then add a user to > the acl_users > folder contained in my FilteringFolder. I define a new role > for this user > and assign it to my new user. From the security tab, I let > my new role > have access to 'View management screens', but nothing else. > I then close > my browser and reopen it. I try to access the management > interface to my > folder using the URL given above. This time, instead of > authenticating as > the super user, I authenticate as my new user. Now, instead of zope > halting, I get the default index_html screen for the folder. > I don't see > contents, and as far as I can tell, my manage_main is never > invoked. I > don't understand this. I'm sure this is some permission > problem, but I > haven't been able to figure it out. Can anyone help explain > what might be > happening and what I would need to correct to make this work? I can > provide more information if that would help. I still don't know for sure, as I don't have the time to investigate, but I think there are some problems with the security interface, making security too tight. It just doesn't work as expected. Try this: Create your Role and user in the top-level acl_users folder. Then give that Role permission to view management screens either on the top-level folder or on your own product. -- Martijn Pieters, Software Engineer | Digital Creations http://www.digicool.com | Creators of Zope http://www.zope.org | mailto:mj@digicool.com ICQ: 4532236 | PGP: http://wwwkeys.nl.pgp.net:11371/pks/lookup?op=get&search=0xA8A32149 -------------------------------------------

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RE: [Zope-dev] Transactions
by Martijn Pieters 24 Feb '00

24 Feb '00

From: Petr Knapek [mailto:knapek@knapek.pvt.net] > Hi Zopists, > is there any possibility to put more information into transaction > description inside the UNDO tab in the manage screen? I am using Zope > 2.1.3 version. I think, that additional information such object type > (DTML Method, DTML Document ...) and what was made with this object > could help. That is not really possible, as a transaction can comprise much more than creating or changeing one object. I can add, delete, and change several objects at once. In fact, even just adding an object, changes the container it is added to. And then, if the object is CatalogAware, the catalog gets updated as well. All in one transaction. -- Martijn Pieters, Software Engineer | Digital Creations http://www.digicool.com | Creators of Zope http://www.zope.org | mailto:mj@digicool.com ICQ: 4532236 | PGP: http://wwwkeys.nl.pgp.net:11371/pks/lookup?op=get&search=0xA8A32149 -------------------------------------------

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Re: [Zope-dev] i18n of zope managed contents
by Tres Seaver 24 Feb '00

24 Feb '00

fog(a)mixadlive.com (Federico Di Gregorio) wrote: > > hi *, > > we are starting to build two *big* (international) sites and we > have the need to localize them from the start. i've looked up every > product on the zope site and read the (only?) document about l10n available: > the "Changing Contexts in Zope" text. i still don't see a clean and simple > solution, so i am thinking about writing a product to help with localization. > but i don't want to reinvent the wheel so here's what i am trying to do. > (comments and pointers to documentation are welcome!) > > ** THE SIMPLIEST WAY ** > > create an L10N object able to render its contents accordingly to a > global variable (e.g., a cookie.) you just set one property for every > language (property name == language id) and you are done. i can also > throw in some nice dtml to let the translators do their job inside > zope in the properties tab, etc... the main problem here is exponential > object growth. a complex page can easily need teens or hundreds of such > objects. > > ** THE IMHO BEST WAY ** > > subclass the Folder object and add (i don't even know if that is possible, > no documentation about it) a new kind of property, lets call it "L10NText." > when the L10NFolder is asked for data, it returns the right translation, > based on the same global variable as above. write some pretty complex dtml > that lets you add L10NText, and, for every L10NText var, add translations. > This approach keeps the number of objects low and all the translated text > is some well-defined place. > > what do you zope gurus think about it? The ZI18N product in my Zope.org folder does something like this: http://www.zope.org/Members/tseaver/ZI18N I am CC'ing the Zope I18N Project mailing list (zip(a)eevolute.com) -- you probably want to subscribe there as well (http://www.eevolute.com/mailman/listinfo/zip) -- ========================================================= Tres Seaver tseaver(a)palladion.com 713-523-6582 Palladion Software http://www.palladion.com

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Transactions
by Petr Knapek 24 Feb '00

24 Feb '00

Hi Zopists, is there any possibility to put more information into transaction description inside the UNDO tab in the manage screen? I am using Zope 2.1.3 version. I think, that additional information such object type (DTML Method, DTML Document ...) and what was made with this object could help. Thanks, Petr -- Petr Knápek PVT.NET, e-mail: petr.knapek(a)pvt.net, tel:+420-5-41 558 394 PVT a.s. - pvt.net, Veveří 102, 659 10 Brno, Czech Republic

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