May 2000 - Zope-Dev - Zope lists

TransparentFolders version 0.1 released
by Shane Hathaway 02 May '00

02 May '00

Zopistas, I've made the first version of TransparentFolders available. http://www.zope.org/Members/hathawsh/TransparentFolders See the description online. It's easy to use; just add a Transparent Folder to any Folder and the folder will effectively acquire from all contained transparent folders. There are currently no rules for selecting among overloaded transparent objects; that issue can be dealt with later. This is just a proof of concept and something to try out. It seems to be plenty fast enough except when used with the version of Zope in the CVS repository, where it slows down the startup procedure dramatically. Versions 2.1.6 and below don't seem to suffer from the slowdown. The slowdown is apparently related to the new help system. The bulk of the product (which is less than 5K compressed!) is a patch to ObjectManager which causes it to search for transparent objects when necessary. I took advantage of Python's flexibility to patch ObjectManager without actually overwriting it (that's why it works with multiple versions of ObjectManager). There is a chance that some product out there will conflict with the patch, however. I recommend you make a backup of your Zope installation (or if you're savvy, just back up lib/python/OFS/__init__.py) because it does need to modify one source file directly. If TransparentFolders conflicts with another product, you should be able to simply remove the lib/python/Products/TransparentFolders directory and the patch will be gone. Anyway, good luck. It should be very useful for many Zopistas! Shane

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(New-style) Property Sheets in traditional (Python) products: an example example
by Mike Fletcher 02 May '00

02 May '00

Only reference I can find to this topic is http://zope.nipltd.com/public/lists/dev-archive.nsf/0a8715d5f3c7b6a3802568c1 006328f7/28e1ed0f8d7efdc980256879003d36d8 , which seems to have gone unanswered. So, since it took me so long to figure out (mostly because I kept trying to put things into the class, not the instance, and 'cause I didn't realise that the newer property sheet mechanisms don't want to "pollute" the namespaces of the instance), figured I'd post an example of using the PropertySheet/PropertySheets constructs. Notes: I'm just guessing with a lot of this stuff, hopefully if there's problems someone can point them out. Use at your own risk, and take with a grain of salt :) . I never could get the DefaultProperties mechanism to work (it's what I was really wanting to use, doing the work with the PropertySheets stuff means a lot of code re-writing). Is there a better/standard mechanism for getting properties than the getProperty function in the example? Seems this kind of access should be included with the basic property system. I couldn't use PropertyManager because of limitations on datatypes it will support. Haven't been able to get write-only properties to work. They either complain that I'm trying to overwrite them when i use the property management interfaces, or they turn to "" strings. Neither old nor new property addition interfaces allow for adding datetime or list property types. Enjoy, Mike 8<_____________ event2.py ___________ __doc__ = """Event Product Module""" __version__ = '0.1' from Globals import HTMLFile from Globals import MessageDialog from Globals import Persistent import OFS.SimpleItem from OFS.PropertySheets import PropertySheets, PropertySheet import Acquisition # Various acquisition types. import AccessControl.Role # Zope Security management. import DateTime manage_addEvent2Form = HTMLFile('event2Add', globals()) def manage_addEvent2(self, id, REQUEST=None): '''Add an event object ''' newEvent = Event( REQUEST ) newEvent.id = id self._setObject( id, newEvent ) if REQUEST is not None: return self.manage_main(self, REQUEST) class Event( OFS.SimpleItem.Item, # A simple Principia object. Not Folderish. Persistent, # Make us persistent. Yaah! Acquisition.Implicit, # Let us use our parent's variables and methods. AccessControl.Role.RoleManager # Security manager. ): meta_type='VRPilot Event' index_html =HTMLFile( 'event2Index', globals() ) event2_display_rows = HTMLFile( 'event2_display_rows', globals() ) manage_main = HTMLFile( 'event2Edit', globals() ) manage_propertiesForm = manage_main # gets around assumption in propertysheet code manage_options = ( {'label':'Edit', 'action':'manage_main'}, {'label':'View', 'action':'index_html'}, # should do something more intelligent than hard-coding in a real app {'label':'Properties', 'action':'properties/default/manage'}, {'label':'Security', 'action':'manage_access'}, ) __ac_permissions__ = ( ('View', ('index_html', '')), ('View management screens', ('manage', 'manage_main', 'getProperty')), ('Manage properties', ('properties',)), ) # these aren't used here, they are copied into the default property sheet _properties = ( {'id':'title', 'type': 'string', 'mode':'w', "meta": {}}, {'id':'description', 'type': 'text', 'mode':'w', "meta": {}}, {'id':'location', 'type': 'string', 'mode':'w', "meta": {}}, {'id':'startdate', 'type': 'datetime', 'mode':'w', "meta": {}}, {'id':'enddate', 'type': 'datetime', 'mode':'w', "meta": {}}, ## {'id':'creationdate', 'type': 'datetime', 'mode':'w', "meta": {}}, ## {'id':'creator', 'type': 'string', 'mode':'w', "meta": {}}, ) def __init__( self, REQUEST= None ): # simple attirbutes self.creationdate = DateTime.DateTime() self.creator = REQUEST.AUTHENTICATED_USER.getUserName() ### Build property sheets... self.properties = PropertySheets() props = PropertySheet( 'default' ) props._properties = self._properties props._extensible= 0 # don't allow definition of new properties # the default values for the properties props.title = "" props.description = "" props.location = "" props.startdate = DateTime.DateTime() props.enddate = DateTime.DateTime() # add the default sheet to the set of sheets self.properties.__of__( self ).addPropertySheet( props ) # now configure the property sheet... self.properties.get('default').manage_editProperties( REQUEST ) def getProperty( self, name, default=None ): ''' Retrieve value of a property by name, from whatever property sheet it is stored in If the property isn't valid for any sheet, return default ''' for sheet in self.properties: if sheet.hasProperty( name ): return sheet.getProperty( name, default ) return default __________________________________ Mike C. Fletcher Designer, VR Plumber http://members.home.com/mcfletch

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Trouble with trees and XML
by Christian Wittern 02 May '00

02 May '00

Hi there, I am having trouble with the tree tag recently... I am trying to display a moderately complex XML Document. I want to have a navigator in one frame and links to the main-frame. I am trying to use the tree tag for the navigator part, since the XML is also kind of a tree structure. I am using the XML Document product 1.0a6, which parses the document in a nice tree structure. The problem is, I don't want all the elements to show up in the tree, rather I want to select them based on the name of the element. I have elements like 'head' and 'title', which should show up in the tree, but the other should be ignored. Any ideas how this could be done? Sigh, any help appreciated... All the best, Christian

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Zope/Python Object Persistence
by Adam Pawliuk 02 May '00

02 May '00

Hi, Is there a way that I can maintain persistent python objects in memory through the Zope Server? As a simple example if I create a counter in a python module and access it through an external method, the module seems to get reloaded every so often, so the counter will get reset. Can I avoid this? Basically I just want to keep a persistent hashtable/Dictionary. MODULE: ************************************************************* __persist = {}; __persist['count'] = 0; def getNextCount(): __persist['count'] = int( __persist['count'] )+1 return __persist['count'] ************************************************************ External method in DTML: <dtml-var "getNextCount()"> thanks in advance

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Re: [Zope-dev] Adding Pike ability to Zope
by Tres Seaver 02 May '00

02 May '00

Chris Withers <chrisw(a)nipltd.com> scribbled: > I guess chuck it in the collector as a suggestion. > > If you give it a high priority, Tres Seaver will probably get back to you > soon :-) What, you think I have a kibobot running here? > http://classic.zope.org:8080/Collector Exactly -- here is the recipe, in case you aren't yet diff-aware: 1. Check out the latest CVS tree (see http://www.zope.org/Resources/CVS for how). 2. Modify lib/python/OFS/DTMLDocument.py to support your patch. 3. Create a "context" or "unified" patch against the original, e.g.:: cvs diff -c lib/python/OFS/DTMLDocument.py or:: cvs diff -u lib/python/OFS/DTMLDocument.py 4. Submit it as "Feature Request w/ Patch", cutting and pasting the output from step #3 into the "Patch" field. Your chance of getting the patch accepted soonest correlates strongly with: * How easy it is to apply (which is why I recommend checking out the "latest-and-greatest" CVS first -- patches against earlier versions are painful to apply and test). * How easy it is to understand ("easy" patches, with clear intents and "obvious" scope qualify as "low-hanging fruit" when triage time hits). Tres. -- ========================================================= Tres Seaver tseaver(a)digicool.com tseaver(a)palladion.com

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absolute_url() and DTML Methods
by David Brown 02 May '00

02 May '00

Why is it that when I call absolute_url() on a DTML Method, I get the URL of the enclosing container, not the DTML Method within that container? Is there an equivalent method that will give me the real location of the DTML Method? Quick reproduction scenario: root+ | +Folder | +DTML Method DTML Method contains: <dtml-var standard_html_header> <dtml-var "absolute_url()"> <dtml-var standard_html_footer> Navigating to the method and hitting "view" gives me the URL of Folder. dave

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Comparison inconsistency with ExtensionClass
by Greg Ward 01 May '00

01 May '00

Hi all -- I seem to have discovered an inconsistency in the semantics of object comparison between plain old Python instances and ExtensionClass instances. (I've cc'd python-dev because it looks as though one *could* blame Python for the inconsistency, but I don't really understand the guts of either Python or ExtensionClass enough to know.) Here's a simple script that shows the difference: class Simple: def __init__ (self, data): self.data = data def __repr__ (self): return "<%s at %x: %s>" % (self.__class__.__name__, id(self), `self.data`) def __cmp__ (self, other): print "Simple.__cmp__: self=%s, other=%s" % (`self`, `other`) return cmp (self.data, other) if __name__ == "__main__": v1 = 36 v2 = Simple (36) print "v1 == v2?", (v1 == v2 and "yes" or "no") print "v2 == v1?", (v2 == v1 and "yes" or "no") print "v1 == v2.data?", (v1 == v2.data and "yes" or "no") print "v2.data == v1?", (v2.data == v1 and "yes" or "no") If I run this under Python 1.5.2, then all the comparisons come out true and my '__cmp__()' method is called twice: v1 == v2? Simple.__cmp__: self=<Simple at 1b5148: 36>, other=36 yes v2 == v1? Simple.__cmp__: self=<Simple at 1b5148: 36>, other=36 yes v1 == v2.data? yes v2.data == v1? yes The first one and the last two are obvious, but the second one only works thanks to a trick in PyObject_Compare(): if (PyInstance_Check(v) || PyInstance_Check(w)) { ... if (!PyInstance_Check(v)) return -PyObject_Compare(w, v); ... } However, if I make Simple an ExtensionClass: from ExtensionClass import Base class Simple (Base): Then the "swap v and w and use w's comparison method" no longer works. Here's the output of the script with Simple as an ExtensionClass: v1 == v2? no v2 == v1? Simple.__cmp__: self=<Simple at 1b51c0: 36>, other=36 yes v1 == v2.data? yes v2.data == v1? yes It looks as though ExtensionClass would have to duplicate the trick in PyObject_Compare() that I quoted, since Python has no idea that ExtensionClass instances really should act like instances. This smells to me like a bug in ExtensionClass. Comments? BTW, I'm using the ExtensionClass provided with Zope 2.1.4. Mostly tested with Python 1.5.2, but also under the latest CVS Python and we observed the same behaviour. Greg -- Greg Ward - software developer gward(a)mems-exchange.org MEMS Exchange / CNRI voice: +1-703-262-5376 Reston, Virginia, USA fax: +1-703-262-5367

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RE: [Zope-dev] Zope`s FTP-server
by Amos Latteier 01 May '00

01 May '00

> How does Zope`s FTP-server work? It tries to translate FTP commands into method calls on Zope objects. >I found myself inside a > database when I > logged in, or at least that what it looked like. Is there > anyway to make or > access ordinary folders, like an ordinary ftp-account, using > this part of > Zope? The FTP server provides access to Zope objects only. It doesn't provide any special access to the filesystem. > Can anybody point me to a document etc. that explains > what happens, > preferrably not the source itself. Right now the source is about all there is in terms of documentation. There are comments in ZServer/FTPServer.py that explain some details about security, etc. In general the FTP server allows you to edit Zope documents as though they were text files on a FTP server. Many folks find this easier than typing in textareas on web pages. -Amos -- Amos Latteier mailto:amos@digicool.com Digital Creations http://www.digicool.com

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zodb question
by cs＠comlounge.net 01 May '00

01 May '00

Hi! I am trying to figure out how actually Zope works in order to decide if I can use Zope or components of it for my own projects (or maybe extend Zope and then doing these projects with Zope). One question which comes to my mind is simple how objects are stored. Are they stored directly with the given hierarchie or are they simply put into the database with a unique ID and the mapping to a directory structure is not directly bound to the object? Or another way round: Do Folders store their list of children in a object attribute and thus in the database or do they get this information from somewhere else? (I've tried to find this in the source but I was a little confused which class now derives what from which other class ;-) Is there any class browser for Python?) Implications of these questions would be if it' easily possible to put an object into more than one folder. And related questions are: How can I access the OID or the list of children of an object/folder ? Interesting would this be when trying to do some sort of SharedFolder class or similar things. best, Christian PS: If you're interested in some more details of what I am thinking a good structure for shared data might be please tell me.. :) Maybe it's even not that good as I think it is now.. ;-)

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Escape characters in dtml
by Adam Pawliuk 01 May '00

01 May '00

Hi, I'm having problems trying to escape a double quotes in a DTML call. For example: <dtml-call "REQUEST.set('FUTURE_URL','<A href="adocument?id=133">click</A>' )"> The double quotes for the 'href' cause problems with the expression double quotes. I tried escaping with \" but this doesn't work either. Any suggestions? Thanks in advance.

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