Mailman 3 February 2002 - Python-Dev

new property factory arguments
by john coppola 18 Feb '02

18 Feb '02

Hello python developers. After discussions with Fred about defining how property objects are created, I decided to give it a whirl myself. After about minute of piddling, I came up with something I thought would be a hack but is quite interesting. Ultimately, this is what I came up with. class Foo(object): def __get__(self, container): print "this is get" print "self:", type(self) print "container:", type(container) print def __set__(self, container, value): print "this is set" print "self:", type(self) print "container:", type(container) print "value:", value print def __del__(self, container): print "this is del" print "self:", type(self) print "container:", type(container) print class Spam(object): x=property(Foo()) I feel this has the benefit of encapsulating the x property from the Spam object. If coupling is needed, then access to Spam can be obtained via container. This was the interesting hack I was talking about. I first tried it without container and got an error, but then I decided to see what that second argument was like hummm, interesting and I liked it. What's really cool is that Foo can be used by a completely separate class. Perhaps Foo is a singleton for a DB connection. A single connection could be created in __new__, and other attribute details created in __init__. So class Spam is decoupled from what is going on in Foo. Whereas the former syntax, this was not possible. I've attached a descrobject.diff file to this email as well as testprop.py. (I've never tried sending an attachment to python-dev, I hope it works.) Enjoy, John Coppola __________________________________________________ Do You Yahoo!? Yahoo! Sports - Coverage of the 2002 Olympic Games http://sports.yahoo.com *** PythonOrig/Python-2.2/Objects/descrobject.c Sat Dec 15 00:00:30 2001 --- PythonDev/Python-2.2/Objects/descrobject.c Sun Feb 17 21:52:55 2002 *************** *** 1003,1024 **** } static int ! property_init(PyObject *self, PyObject *args, PyObject *kwds) { ! PyObject *get = NULL, *set = NULL, *del = NULL, *doc = NULL; ! static char *kwlist[] = {"fget", "fset", "fdel", "doc", 0}; ! propertyobject *gs = (propertyobject *)self; ! ! if (!PyArg_ParseTupleAndKeywords(args, kwds, "|OOOO:property", ! kwlist, &get, &set, &del, &doc)) ! return -1; ! ! if (get == Py_None) ! get = NULL; ! if (set == Py_None) ! set = NULL; ! if (del == Py_None) ! del = NULL; Py_XINCREF(get); Py_XINCREF(set); --- 1003,1023 ---- } static int ! property_init(PyObject *self, PyObject *args, PyObject *kw) { ! PyObject *get=NULL, *set=NULL, *del=NULL, *doc=NULL, *arg=NULL; ! static char *kwlist[] = {"object", 0}; ! propertyobject *gs = (propertyobject *)self; ! if (!PyArg_ParseTupleAndKeywords(args,kw,"|O:property",kwlist,&arg)) ! return -1; ! ! get = PyObject_GetAttrString(arg,"__get__"); ! set = PyObject_GetAttrString(arg,"__set__"); ! del = PyObject_GetAttrString(arg,"__del__"); ! doc = PyObject_GetAttrString(arg,"__doc__"); ! if (get == Py_None) get = NULL; ! if (set == Py_None) set = NULL; ! if (del == Py_None) del = NULL; Py_XINCREF(get); Py_XINCREF(set); *************** *** 1034,1049 **** } static char property_doc[] = ! "property(fget=None, fset=None, fdel=None, doc=None) -> property attribute\n" "\n" ! "fget is a function to be used for getting an attribute value, and likewise\n" ! "fset is a function for setting, and fdel a function for del'ing, an\n" ! "attribute. Typical use is to define a managed attribute x:\n" "class C(object):\n" ! " def getx(self): return self.__x\n" ! " def setx(self, value): self.__x = value\n" ! " def delx(self): del self.__x\n" ! " x = property(getx, setx, delx, \"I'm the 'x' property.\")"; static int property_traverse(PyObject *self, visitproc visit, void *arg) --- 1033,1050 ---- } static char property_doc[] = ! "property(object) -> property attribute\n" "\n" ! "__get__ is a function to be used for getting an attribute value, and\n" ! "likewise __set__ is a function for setting, and __del__ a function for\n" ! "del'ing, an attribute. Typical use is to define a managed attribute x:\n" "class C(object):\n" ! " def __get__(self, container): return self.__x\n" ! " def __set__(self, container, value): self.__x = value\n" ! " def __del__(self, container): del self.__x\n" ! "\n" ! "class D(object):\n" ! " x = property(object=C(), \"I'm the 'x' property.\")"; static int property_traverse(PyObject *self, visitproc visit, void *arg) __doc__="""\ class Foo(object): def __get__(self, container): print "this is get" print "self:", type(self) print "container:", type(container) print def __set__(self, container, value): print "this is set" print "self:", type(self) print "container:", type(container) print "value:", value print def __del__(self, container): print "this is del" print "self:", type(self) print "container:", type(container) print __doc__ = "this is doc" """ exec __doc__ class Spam(object): x=property(Foo()) print __doc__ a=Spam() a.x=5 print "getting:", a.x del a.x

3 3

SSL support in _socket
by M.-A. Lemburg 18 Feb '02

18 Feb '02

I have a problem with SSL support in _socket and the way setup.py does the autodetection: even though SSL may be installed on the system, it seems that they changed the exposed APIs between patch level releases. As a result, _socket compiles but the import fails on platforms which have the wrong OpenSSL version installed. setup.py then simply removes _socket from the extension list and builds Python without socket support which is a really Bad Thing since _socket without SSL support compiles just fine. What can we do about this ? Since auto-detection is happening rather early in setup.py it doesn't seem possible to apply some fallback scheme depending on extra knowledge for the various modules. Perhaps we should simply let setup.py build two extensions: _socket (without SSL) and _socketssl (with SSL) ?! If the _socketssl build or import fails for some reason, Python could still pick up the _socket extension in socket.py. Comments ? -- Marc-Andre Lemburg CEO eGenix.com Software GmbH ______________________________________________________________________ Company & Consulting: http://www.egenix.com/ Python Software: http://www.egenix.com/files/python/

6 16

OS/2 EMX port build directory committed
by Andrew MacIntyre 17 Feb '02

17 Feb '02

I have committed PC/os2emx and its contents. If disaster results, please cc this e-mail address, as I haven't been able to get into my main e-mail account (ISP equipment problems). Andrew I MacIntyre "These thoughts are mine alone ..." Email: andymac(a)bullseye.apana.org.au (preferred) | Snail: PO Box 370 andymac(a)pcug.org.au (alternate) | Belconnen ACT 2616 andrew.macintyre(a)aba.gov.au (work) | Australia

2 2

%#x/%#X format conversion patches for review
by Andrew MacIntyre 17 Feb '02

17 Feb '02

Following on from discussion of the patch I uploaded containing OS/2 EMX changes to the Python core, I have uploaded patches to Objects/stringobject.c and Objects/unicodeobject.c to simplify the mess of dealing with these format conversions in the face of Python's preferences vs the C standard, C standard violations, and bugs. http://sf.net/tracker/?func=detail&aid=450266&group_id=5470&atid=305470 (this is my "Python core" OS/2 EMX patch in the Patch manager) I have assigned the patch to Martin von Loewis; if they should be moved to a separate patch for future reference, please let me know. Andrew I MacIntyre "These thoughts are mine alone ..." Email: andymac(a)bullseye.apana.org.au (preferred) | Snail: PO Box 370 andymac(a)pcug.org.au (alternate) | Belconnen ACT 2616 andrew.macintyre(a)aba.gov.au (work) | Australia

2 3

sendall patches not in 2.2?
by Martin v. Loewis 17 Feb '02

17 Feb '02

I wonder why Anthony's Grand sendall patch never found its way into Python 2.2, see http://aspn.activestate.com/ASPN/Mail/Message/Python-checkins/956422 http://mail.python.org/pipermail/python-bugs-list/2001-December/009299.html https://sourceforge.net/tracker/index.php?func=detail&aid=516715&group_id=5… Unless there are any objections, I'll forward this patch to 2.2 (not sure what to do with imaplib, since that has been taken care of with an explicit loop in Python meanwhile). Regards, Martin

2 1

Reminder: Python track at OSCON -- Deadline March 1!
by David Ascher 16 Feb '02

16 Feb '02

Reminder: The O'Reilly Open Source Convention (July 22-26, 2002 -- San Diego, CA) is accepting proposals for tutorials, talks, panels, and lightning talks. See the Call for Participation in the Python and Zope track on python.org. Proposals are due by March 1, so don't wait a moment longer! Details available at: CFP URL: http://www.python.org/workshops/oscon2002/cfp.html form: http://conferences.oreillynet.com/cs/os2002/create/e_sess Cheers, -- David Ascher [Guido's the program chair, but he's on the road, so I'm filling in] PS: Feel free to resend this to whatever mailing lists may be interested.

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spice for PEP 282
by David Goodger 16 Feb '02

16 Feb '02

Here's some spice for the logger recipe. Please season to taste. Abstract ======== The dps.utils.Reporter class (http://docstring.sf.net/dps/utils.py) implements a logger but with *multiple* thresholds per category (stream/channel). Similarly to log4j, there's a "warninglevel" threshold, which determines if a message gets sent to the warning stream (sys.stderr). There's also an "errorlevel" threshold which determines if a message is converted into a *raised exception*, potentially halting processing. And a "debug" flag which turns debug messages on or off independently of the "warninglevel" threshold. I suggest that the Python stdlib logging module adopt some of these features. Background ========== I've been working on the DPS & reStructuredText projects (soon to be merged and officially renamed to "Docutils") on and off for some months now. Docutils will parse texts (files or docstrings) into DOM-like document trees, then convert them to HTML etc. Early on I saw the need to insert "system_message" feedback elements of different levels into the doctree and implemented dps.utils.Reporter. I included thresholds for logging to sys.stderr and raising exceptions, initially with only one setting (like log4j with only the root "category" set). This Reporter class has been very successful As a pointed reminder of how wheels are continually reinvented, I learned about log4j (just before the python-dev effort got underway; I probably read the same message that got Guido started). I already had 4 message levels (what log4j called "logging priorities"), and log4j's notion of "logging categories" seemed a powerful one, so I retrofitted the dps.utils.Reporter class with support for categories. I also added a "debug" category, which I had been handling separately.

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Re: [Python-Dev] [Python 2.2 BUG] pickle/cPickle does not find __slots__
by john coppola 16 Feb '02

16 Feb '02

I'm definitely in preference to slot versus attribute. But may be we could just use def. class Foo: def a def b def c def somemethod(self): pass The distinction being the def statement is "unbound" so to speak. humm.... the code is not clear enough. class Foo: slot a slot b slot c def foo(): pass Better, much better. class Foo: slot a is str slot b is float slot c is property of float def foo(self): pass I like this. It reads like sentences. (remember, 'of' modified property to ensure that the fget return type would be correct and fset passed in object would be correct) I didn't much care for Groucho's notation, particularly if a slot could have multiple types, why bother assigning types to it at all. It should definitely be singular. One to one. The concept of slot does not need to be solely related to attributes within a class. Why not reserve slots for a methods, classes within a module, modules imported within modules. Then it will be easier to see the overall picture. Does the slot pattern relate to every object in python? I think it does. That's when the real benefit comes in. If python could utilize this pattern in every aspect, the big performance boost will occur. In a strange way slots has made python even more dynamic than it ever was. Prior to slots, objects had a static c structure. Slots enables variability in another dimension for the underlying C struct. On the outside it looks like python is becoming static, but what's really going on under the hood is quite the contrary. Definitely more burden on the compiler to build correct references and make the correct substitutions. __________________________________________________ Do You Yahoo!? Got something to say? Say it better with Yahoo! Video Mail http://mail.yahoo.com

1 0

IRC?
by Skip Montanaro 16 Feb '02

16 Feb '02

Is there a set time people congregate on IRC (#python-dev @ irc.openprojects.net)? Skip

2 1

Re: Re[2]: [Python-Dev] syntactic sugar idea for {static,class}methods
by Michael Hudson 15 Feb '02

15 Feb '02

Gareth McCaughan <gmccaughan(a)synaptics-uk.com> writes: > On Fri, 15 Feb 2002 04:25:55 -0500, Oren Tirosh <oren-py-d(a)hishome.net> wrote: > > The modifier order [memoize, staticmethod] sounds more like the sentence > > "foo is a memoized staticmethod" - at least in English it does. In French, > > Hebrew and several other languages it's the other way around, but Python > > is definitely English-oriented. > > Interesting. I read it more as: "Define a function, then memoize it > and make it a static method". That's what my patch does, too, but I can't remember whether this was by accident or design :-/. Incidentally, I'm not sure class C: def s(): print 1 s = memoize(staticmethod(s)) would actually work (s would have type 'function'). I guess memoize could made cleverer than the version I posted. Cheers, M. -- "declare"? my bogometer indicates that you're really programming in some other language and trying to force Common Lisp into your mindset. this won't work. -- Erik Naggum, comp.lang.lisp

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Python-Dev February 2002