March 2004 - Zope - Zope lists

Interfaces in Zope 2.5, 2.7, and 3.x
by Terry Hancock 01 Mar '04

01 Mar '04

I have a product that uses a component/interface model internally. I wrote this against the "scarecrow" Interface module in Zope 2.5.1. However that module has limitations. One particular one is what I call a "SubInterface" -- which is a special case of Interface.Attribute (a subclass of it) that asserts that an object contained within a parent interface implements a particular interface. So, for example, a SubInterface might say that in order to conform to interface "foo", the attribute "bar" must point to an object which implements "Mapping" (e.g. a dictionary -- it doesn't have to *be* a dictionary, but it must act like one). Anyway, I wrote my own interface module to do this, extending the Interface module in Zope 2.5.1 (which lacks this feature). All of my code actually imports interface support from my module instead of directly from Interface. For unrelated reasons, though, I had to upgrade to Zope 2.7 (and someday, I imagine I'll want to consider moving to Zope 3.x). My first attempt with Zope 2.7, though yields total breakage! The Interface module has been extensively overhauled, method names changed, etc. After giving up on "just fixing a few name- changes", which seems to be woefully inadequate, I decided to try to lift the old Interface module -- but now Zope reads the "__implements__" attribute and isn't happy if it isn't one of its own interface objects! """ Installing Narya ... Traceback (most recent call last): File "./testNaryaInterface.py", line 11, in ? ZopeTestCase.installProduct('Narya') File "/usr/local/narya/z2.7.0/lib/python/Testing/ZopeTestCase/ZopeLite.py", line 119, in installProduct get_folder_permissions(), raise_exc=1) File "/usr/local/narya/z2.7.0/lib/python/OFS/Application.py", line 732, in install_product initmethod(context) File "/usr/local/narya/zope/Products/Narya/__init__.py", line 25, in initialize icon='www/Icon/Thread.gif') File "/usr/local/narya/z2.7.0/lib/python/App/ProductContext.py", line 176, in registerClass interfaces = instancesOfObjectImplements(instance_class) File "/usr/local/narya/z2.7.0/lib/python/Interface/Implements.py", line 120, in instancesOfObjectImplements visitImplements(implements, klass, r.append, getInterface) File "/usr/local/narya/z2.7.0/lib/python/Interface/Implements.py", line 90, in visitImplements raise Exceptions.BadImplements( Interface.Exceptions.BadImplements: __implements__ should be an interface or tuple, not a instance pretending to be a Interface """ (Seems I'm a pretender ;-) ). Now, I can implement a new module based on the Zope 2.7 Interface -- but a close look at that seems to show that it, too, is rather experimental (lots of stubs, not-yet-implemented attributes, etc). So I'm also sort of interested in the "interface" module in Zope X3. It appears that some new bells and whistles have been added to the Interface module (e.g. what's a "superinterface"?). Any chance, I'm wondering if "SubInterface" is now redundant? Also, is there a general guide to "best practice" of using / learning the Interface module? I note there are now interfaces defined for the interface module (cool!), and it looks like some self-documentation has been implemented. The biggest problem (and this seems to be the usual problem with "self-documenting" tools) is that there doesn't seem to be a "start here" defined anywhere. So you wind up starting somewhere in the middle and wasting a lot of time trying to decipher the big picture from lots of details, which is backwards. It'd be nicer if there was a "README" to get you started on this, maybe define some jargon, etc. It's really hard to infer what the overall design concept is by only looking at these details -- in particular, I want to know what was conceptually changed from the older Interface module in 2.5.1. This seems to also be a problem with combining Zope 3 and Zope 2 interfaces, as was suggested by a post on the Zope3 mailing list: http://mail.zope.org/pipermail/zope3-dev/2003-December/009023.html (and following -- note that "__interfaces__" should read "__implements__" in the original post). Martijn's suggestion was to use an alternate name for the "__implements__" attribute. I suppost I could do that -- call mine "__narya_interfaces__", but that sounds ugly. In particular, I don't really want my interfaces module to actually *conflict* with Zope's. I also note that the post from the Zope3 list suggests that I shouldn't really be directly assigning "__implements__", but using something called "implements()". Hmm. That's different too -- is there any good starting place for understanding Zope3's "interface" module? And how different are the Zope 2.7 / Zope X3 interface modules? If I re-write my module to conform to Zope 2.7, will I just have to do it again? Could I instead leap ahead and use the Zope X3 interface module in Zope 2.7? Also, since I'm posting to Zope3-dev as well -- what do you think of the SubInterface concept? Should I be contributing code directly to Zope X3's interface instead of subclassing it? All it requires is something like: """ class SubInterface(Attribute): """ A SubInterface is an Attribute with an assigned Interface. """ def __init__(self, __name__=None, __doc__=None, api=None, optional=0): self.__name__=__name__ self.__doc__=__doc__ or __name__ self.api = api self.optional = optional """ Which is what my module defines -- the trickier bit is defining a function to recursively check SubInterfaces. That's included too, but it breaks due to major API changes in Interface. Cheers, Terry -- Terry Hancock ( hancock at anansispaceworks.com ) Anansi Spaceworks http://www.anansispaceworks.com

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LDAPUserFolder getProperty('..')
by Aitzol Naberan Burgaña 01 Mar '04

01 Mar '04

1 0

Zope + KinterBasDB problem
by fowlertrainer＠anonym.hu 01 Mar '04

01 Mar '04

Hello ! My problem is that: I developed a small hungarian website with database connections. I have no problem before, because the zope+kidb automatically convert the hungarian characters to from database. (these are: áéíóüöúő - a',e',i',o',u:,o: u',o" - and more...) But I know (because I'm Delphi programmer), the InterBase/FireBird is need the charset for the connection. If it is not same that GDB-s chaset, then IB drop an error: "cannot translit. between character sets, or truncate error", or like this message. Before this point I don't use parameterized queries with hungarian characters, so the problem is not exists for me. But now I need to use it, and the zope (kidb) every time drop this error. The connection string is like that: "192.168.1.17:/mpanni/bha/database/mpanni.gdb sysdba x" I try with this: "192.168.1.17:/mpanni/bha/database/mpanni.gdb sysdba x charset=win1250" but it is not working. How to I set this charset to this database for parameterized queries ? Thanx for every help ! -- Best regards, fowlertrainer mailto:fowlertrainer@anonym.hu

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Zope 2.7.0 has been updated in Superdownloads!
by info＠superdownloads.com.br 01 Mar '04

01 Mar '04

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