July 2000 - Zope-Dev

Proposed interface: Restricted creation
by Itamar Shtull-Trauring 10 Jul '00

10 Jul '00

(URL: http://www.zope.org/Members/michel/Projects/Interfaces/RestrictedCreation) Restricted Creation of Objects The problem - certain types of objects should not be added except in certain places or with certain restrictions. For example, we may want to make sure Laundry objects are only added inside Luggage objects, and nowhere else. Or we may want to make sure that an object is added only if there's a MailHost in it's acquistion path. How do we ensure this? I propose a Restricted Creation Interface - when an ObjectManager constructs it's Add list in manage_main, it first checks with each addable class if it's instances can be added in this specific ObjectManager. We do this by calling a class method called _addableIn(), that receives as a parameter the ObjectManager to which we may want to add objects. If the result is not true, instances of this class can't be added, and won't be listed in the Add list. For example, the following code will make the Laundry class show up in the Add menu only in objectmanagers whose meta_type is "Luggage": class Laundry(SimpleItem): """ A Fruit class """ def _addableIn(parent): if parent.meta_type == "Luggage": return 1 else: return 0 I'm not sure how to get from meta_type to class, so I can't show working code, but something like this in ObjectManager.py would do the trick: def filtered_meta_types(self, user=None): # Return a list of the types for which the user has # adequate permission to add that type of object. user=getSecurityManager().getUser() meta_types=[] if callable(self.all_meta_types): all=self.all_meta_types() else: all=self.all_meta_types for meta_type in all: > klass = getClassFromMetaType(meta_type) > > # If the class has a function _addableIn, it must return true or > # that means the class doesn't want to be added to this ObjectManager: > > if not hasattr(klass, '_addableIn') or klass._addableIn(self): > if meta_type.has_key('permission'): > if user.has_permission(meta_type['permission'],self): > meta_types.append(meta_type) > else: > meta_types.append(meta_type) return meta_types Comments? -- Itamar S.T. itamar(a)maxnm.com Fingerprint = D365 7BE8 B81E 2B18 6534 025E D0E7 92DB E441 411C

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_delObject Method
by Heine, Gregor 10 Jul '00

10 Jul '00

Hello! Can anybody tell me, what the 'dp=1' attribute in the _delObject methods of the ObjectManager (OFS/ObjectManager.py) and ZClassMethodsSheet (ZClasses/Method.py) Class are for? I haven't found any method call, where dp is set and the methods themselves don't use it aswell. I would like to use it as a switch for (not) calling the manage_beforeDelete method, when the _delObject method is called by CopySupport.manage_renameObject and CopySupport.manage_pasteObject. In these cases, manage_beforeDelete would not be called. To me that seems to be correct, because during a cut-paste and a rename operation the Objects are not really deleted, they are just temporarily taken out of the object-tree and then inserted again. Are there any problems with that? Or is 'dp' used for another purpose in an older or a newer version of Zope (I use Zope 2.1.6)? -OFS/ObjectManager.py-line 277--------- def _delObject(self, id, dp=1): object=self._getOb(id) if dp: object.manage_beforeDelete(object, self) self._objects=tuple(filter(lambda i,n=id: i['id']!=n, self._objects)) self._delOb(id) --------------------------------------- -OFS/CopySupport.py-line 225 and 259--- ob.aq_parent._delObject(id, 0) --------------------------------------- Thanx, Gregor!

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Python (File) Product Permission Handeling
by Stephan Richter 10 Jul '00

10 Jul '00

Hello everyone, I am writing my own Python Product and it is going well so far, except that some of the default permissions will not transfer. I have an ObjectManager object that contains another ObjectManager-based object. The first inherits the permissions of Zope just fine, but in the second one I am only allowed to view manage_main, but all other self-defined manage screens I am unable to see. For example: I created a manage_blah method, but when I try to view its label (manage_tabs) I get an unauthorized error from the manage_workspace method. The user I am using is Owner and Manager (Zope Version 2.2.0b2). Regards, Stephan -- Stephan Richter - (901) 573-3308 - srichter(a)cbu.edu CBU - Physics & Chemistry; Framework Web - Web Design & Development PGP Key: 735E C61E 5C64 F430 4F9C 798E DCA2 07E3 E42B 5391

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dtml-try/except triggers namespace bug
by Ng Pheng Siong 08 Jul '00

08 Jul '00

Hi, I've run into a bug with <dtml-try/except> with Zope 2.2.0b3. I have a folder called 'root' that looks like this: one (folder) two (folder) three (folder) a_one (dtml method) a_two (dtml method) index_html (dtml method) index_html looks like this: <dtml-try> <dtml-var "_.getitem('a_%s' % id, 1)"> <dtml-except KeyError> Here goes default information. </dtml-try> The idea is to do the following: http://.../root/one --> invoke root/a_one http://.../root/two --> invoke root/a_two http://.../root/one/two --> invoke root/a_two http://.../root/two/one --> invoke root/a_one http://.../root/three --> "Here goes default information." http://.../root --> "Here goes default information." I'm rendering the folders under root (one, two, three, ...) with <dtml-tree>; I want to reconfigure my tree easily while keeping the leaves' content in one place, i.e., in a_one, a_two, etc. in root. The above works with Zope-2.1.6 but not with Zope-2.2.0b3. Here's the traceback: Zope has encountered an error while publishing this resource. Error Type: TypeError Error Value: unexpected keyword argument: error_type Traceback (innermost last): File C:\pkg\Zope220b3\lib\python\ZPublisher\Publish.py, line 222, in publish_module File C:\pkg\Zope220b3\lib\python\ZPublisher\Publish.py, line 187, in publish File C:\pkg\Zope220b3\lib\python\Zope\__init__.py, line 221, in zpublisher_exception_hook (Object: ElementWithAttributes) File C:\pkg\Zope220b3\lib\python\ZPublisher\Publish.py, line 171, in publish File C:\pkg\Zope220b3\lib\python\ZPublisher\mapply.py, line 160, in mapply (Object: index_html) File C:\pkg\Zope220b3\lib\python\ZPublisher\Publish.py, line 112, in call_object (Object: index_html) File C:\pkg\Zope220b3\lib\python\OFS\DTMLMethod.py, line 167, in __call__ (Object: index_html) File C:\pkg\Zope220b3\lib\python\DocumentTemplate\DT_String.py, line 502, in __call__ (Object: index_html) File C:\pkg\Zope220b3\lib\python\DocumentTemplate\DT_Try.py, line 212, in render File C:\pkg\Zope220b3\lib\python\DocumentTemplate\DT_Try.py, line 244, in render_try_except File C:\pkg\Zope220b3\lib\python\DocumentTemplate\DT_Util.py, line 262, in namespace TypeError: (see above) Traceback says the problem is at DocumentTemplate.DT_Util.namespace(). The 2.1.6 and 2.2.0b3 implementations are different. Plugging in 2.1.6's code fixes _this_ problem: def namespace(self, **kw): """Create a tuple consisting of a single instance whos attributes are provided as keyword arguments.""" #return apply(self, (), kw) # XXX ngps - following is the 2.1.6 implementation r=namespace_() d=r.__dict__ for k, v in kw.items(): d[k]=v return r, Cheers. -- Ng Pheng Siong <ngps(a)post1.com> * http://www.post1.com/home/ngps

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package descriptions
by ethan mindlace fremen 07 Jul '00

07 Jul '00

Zopatistas! I have recently changed the product page at http://www.zope.org/Products . If you would be so kind as to change your product description so that the first line contains a meaningful description of your product in plain text, I would appreciate it. Thanks, ethan mindlace fremen Zopatista Community Liason

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BTreeFolder released
by Shane Hathaway 07 Jul '00

07 Jul '00

Zopistas, I had some inspiration today and discovered a simple way to write a BTreeFolder implementation. http://www.zope.org/Members/hathawsh/BTreeFolder/ It works better than I thought it would. It allows you to store thousands (well, I've tested it with only 1536, but I don't know of any limit) of objects with a user interface optimized for such a large folder. Enjoy! And HAPPY INDEPENDENCE DAY! Shane

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Request for amplification on new Product permissions API.
by R. David Murray 07 Jul '00

07 Jul '00

OK, I read Brian's excellent HowTo on the 2.2 Product permissions API, but it unfortunately doesn't give me the answer to my current 2.2 problem (or if it does there's something else I don't know that is preventing me from figuring it out). I'm trying to update EMarket to work under 2.2. EMarket has a shopper object. A shopper's current set of potential purchases is stored on the shopper object in a 'basket' attribute. What gets assigned to this attribute is an instance of a 'Basket' class. It inherits from Persistent and Acquisition.implicit. (Shopper, among other things, inherits from OFS.SimpleItem, by the way.) So, when I access the page that displays the current shopping cart, under 2.2 I get an unauthorized error when the dtml code attemps to access an attribute of the basket object. So, what do I need to do to allow controlled access to this object? I understand that Shopper, inheriting from SimpleItem, already has the access to unprotected subobjects flag. And I'd rather protect the object correctly, anyway <grin>. I tried adding an ac_permissions structure to the class, giving View permission to the attribute that is throwing the unauthorized error, but that doesn't seem to have changed the behavior. Adding the access to subobjects flag also didn't do anything. I created a new shopper/basket just in case the changes don't affect existing objects, but still got the same unauthorized error. --RDM

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Re: [Zope-dev] why does an error in my externalmethod ...
by Dieter Maurer 06 Jul '00

06 Jul '00

Joachim Schmitz writes: > > make the folder from which it was invoked inaccessable ? > > continuing work on my external, I removed all modifications of self, so no > transactions or better modifications of the ZODB took place. During the > development cycle: editing the external methods, testing it through > calling it through the browser, after editing the method the call of > ..../Movies/testForm resulted in a not found error. > also I cannot enter the folder "Movies", if I click on it in the > managementscreen, I also get the not found error. There is no transaction > to undo, I restarted Zope no luck, I tried to delete the folder and get > the error: > > Error Type: SystemError > Error Value: Failed to import class setrecord from module __main__ > .... > The class setrecord is in my external-method. I luckily had packed zodb > shortly before that, and it is just a testserver. So I copied the > Data.fs.old to Data.fs. Till now I could not reproduce the error. I still > have the corrupted Data.fs. You should be very careful, not to store instances of classes defined in external method files in the ZODB. The reason: These Python files are not imported in a standard way, but instead they are read and executed. Therefore, the unpickler is not able to find the classes module, you get the problem you reported. When you need to store class instances in the ZODB, you should define these classes in a standard package. The "Shared" packages is designed for this purpose. Create an appropiately named subpackage (e.g. company name) and put your modules there. In your case, you may have written to a persistent object unintentionally. Dieter

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why does my externalmethod generate a ZODB transaction
by Joachim Schmitz 06 Jul '00

06 Jul '00

Hi, I wrote an external method from which I call a ZSQL-method, this runs fine and returns the correct results, but when I look at the ZODB transactions, I see that for each call of the method a transaction is recorded. Even worse, when I make an error in my method, the folder from which I invoked the method is no longer accesseble. I have to undo the transaction first, that's how I found out that there is a transaction happening. here is the code of the External-method: import string import sys sys.path[0:0]=["/usr/local/Zope-2.1.4/Extensions"] from DocumentTemplate import * def dump(self,EA,**kwa): #return EA,kwa s = " " if hasattr(self,EA): ea = apply(getattr(self,EA),(),kwa) #return ea._names," ",ea._schema ead = ea.__dict__ for r in ead.keys(): s = s + r + " " i=getattr(ea,r) if type(i) == type([]) and len(i) > 0: s = s + str(i) + " " for n in i: s = s + str(n) + " | " s=s+" " elif type(i) == type({}): s = s + str(i) + " " for n in i.items(): s = s + str(n) + " | " s=s+" " return s def workform(self,REQUEST): "Die Masken EinAusgabe" scol = "movie_id" sval = "a%" srel = "like" return dump(self,"Row_search",scol=scol,sval=sval,srel=srel) this dumps the result of the ZSQL-method, I call it from a dtml-method "testForm" like this: <dtml-var standard_html_header> <dtml-var "RForm(REQUEST)"> <--- this calls workform <dtml-var standard_html_footer> when invoking this like .../Movies/testForm I have an entry in the undoable transactions: ...Movies/testForm by super on Jul 4 at 21:21:31 By the way why is the day one day off the machine REDhat 6.2 Zope-2.1.4 has the correct date and shows now: Wed Jul 5 21:49:01 CEST 2000 Mit freundlichen Grüßen Joachim Schmitz AixtraWare, Ing. Büro für Internetanwendungen Hüsgenstr. 33a, D-52457 Aldenhoven Telefon: +49-2464-8851, FAX: +49-2464-905163

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ExtensionClass and __radd__()?
by Greg Ward 06 Jul '00

06 Jul '00

Hi all -- looks like ExtensionClass doesn't recognize/implement the '__radd__()' protocol. Speculation below; first, a demonstration. Normal case: a regular class Number that knows how to add itself to other number-like things: class Number: def __init__ (self, n): self.n = n def __str__ (self): return str(self.n) def __add__ (self, other): return self.n + other __radd__ = __add__ n = Number(37) print n, n + 5, 5 + n The output of this is exactly what you'd expect: 37 42 42 (I have convinced myself that '__radd__()' is called in the "5 + n" case by writing a separate '__radd__()' with a print statement. Everything is sane!) Now the same thing as an ExtensionClass: from ExtensionClass import Base class ECNumber (Base): def __init__ (self, n): self.n = n def __str__ (self): return str(self.n) def __add__ (self, other): return self.n + other __radd__ = __add__ ecn = ECNumber(37) print ecn, ecn + 5, 5 + ecn The output of this is puzzling, to say the least: 37 42 134883149 IOW, "5 + ecn" evaluates to 134883149 -- that's a plain int, I checked with 'type()' on it. If I put this code: print id(ecn), id(5), id(ECNumber), id(Base), id(ExtensionClass) immediately after the last print, I get 135530536 135220848 135568720 1075195712 1075195488 ... which just tells me that the result of "5 + ecn" looks a lot like an id(), but isn't the id() of anything obvious. (Or 5 + any obvious id().) Happens the same with the ExtensionClass code from Zope 2.1.5 or 2.2beta1, and with Python 1.5.2 and the latest CVS Python. Speculation time: I'm guessing that this is similar to the problem with 'isinstance()' and ExtensionClass that I found several months ago, which was heroically debugged by Barry. To recap, it's a mutual finger-pointing bug: Python (Guido) can claim that it's up to ExtensionClass (Jim) to emulate the full semantics of Python classes/instances, but ExtensionClass can claim that Python should be more relaxed in what it accepts as a "class object" or "instance object". I think the relevant code in Python is in Objects/abstract.c, specifically 'PyNumber_Add()' and the BINOP macro: #define BINOP(v, w, opname, ropname, thisfunc) \ if (PyInstance_Check(v) || PyInstance_Check(w)) \ return PyInstance_DoBinOp(v, w, opname, ropname, thisfunc) [...] PyNumber_Add(v, w) PyObject *v, *w; { PySequenceMethods *m; BINOP(v, w, "__add__", "__radd__", PyNumber_Add); [...] My guess is that PyInstance_Check() returns false for ExtensionClass instances. Two possible fixes: loosen up PyInstance_Check(), or loosen up BINOP. Well, it's a nice theory. It doesn't explain why '__add__()' works for ExtensionClass while '__radd__()' does not; perhaps ExtensionClass implements that much of Python's class semantics, but doesn't go as far as '__radd__()'. Other opinions? Greg

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