🌐 Mailman 3 August 2004 - Python-list - python.org

Re: Noob question on PyQt and Qt
by dusty Aug. 1, 2004

Aug. 1, 2004

On Sun, 1 Aug 2004 19:32:10 +0100, Phil Thompson <phil(a)riverbankcomputing.co.uk> wrote: >On Sunday 01 August 2004 6:42 pm, dusty wrote: >> I am learning Python and Qt designer (using eric3). I'm writing an app >> using QCheckList and have succeeded in loading parent and children, >> with checkboxes, with data from a file. I want to programmatically >> check some boxes depending on the string from the list. >> >> This is the code that I use to create the checkbox's: >> ~~~ >> d = QCheckListItem(it, lstI[g:], QCheckListItem.CheckBox) >> self.childlist1.append(d) >> ~~~ >> The first char in each line in 'lstI' determines if the checkbox >> should be checked or not. >> How do I change the checkbox to 'On' (checked) in Python code when the >> checkbox is created? > >Use the setOn() method. > >Phil Thanks Phil.

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Noob question on PyQt and Qt
by dusty Aug. 1, 2004

Aug. 1, 2004

I am learning Python and Qt designer (using eric3). I'm writing an app using QCheckList and have succeeded in loading parent and children, with checkboxes, with data from a file. I want to programmatically check some boxes depending on the string from the list. This is the code that I use to create the checkbox's: ~~~ d = QCheckListItem(it, lstI[g:], QCheckListItem.CheckBox) self.childlist1.append(d) ~~~ The first char in each line in 'lstI' determines if the checkbox should be checked or not. How do I change the checkbox to 'On' (checked) in Python code when the checkbox is created?

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slowdown with massive memory usage
by Hallvard B Furuseth Aug. 1, 2004

Aug. 1, 2004

I have a program which starts by reading a lot of data into various dicts. When I moved a function to create one such dict from near the beginning of the program to a later time, that function slowed down by a factor of 8-14: 38 sec at 15M memory usage, 570 sec at 144M, 330 sec at 200M. Is there anything I can do to fix that? When the program is running, the system has 18M free memory and is not doing any swapping. `python -O' did not help. Python: 2.2.3 configured with --enable-ipv6 --enable-unicode=ucs4 on i386-redhat-linux-gnu (Linux 2.4.21-15.0.2.ELsmp). I'm not sure if upgrading to Python 2.3 is an option at the moment; I'll check if necessary. -- Hallvard

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Re: transforming a list into a string
by bokr＠oz.net Aug. 1, 2004

Aug. 1, 2004

On Sun, 1 Aug 2004 11:00:32 +1000, Andrew Bennetts <andrew-pythonlist(a)puzzling.org> wrote: [...] > >It's a two-liner, not a one-liner (although it could be made into a >one-liner with enough contortions...). > Another contortion ;-) >>> items = ['1','2','7','8','12','13'] assumed defined as before, then one line: >>> ''.join([i%2 and c+'},' or '{'+c+',' for i,c in enumerate(items)])[:-1] '{1,2},{7,8},{12,13}' Regards, Bengt Richter

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Re: transforming a list into a string
by Roy Smith Aug. 1, 2004

Aug. 1, 2004

Andrew Bennetts <andrew-pythonlist(a)puzzling.org> wrote: > It's a two-liner, not a one-liner (although it could be made into a > one-liner with enough contortions...). > > The only other way I could see to expand this solution would be to write it > as: > it = iter(items) > pairs = izip(it, it) > s = ",".join(["{%s,%s}" % i for i in pairs]) > > I don't know if three-liners meet your threshold for verbosity ;) It's better, but I'd unroll it one more step and write: it = iter (items) pairs = izip (it, it) strings = ["{%s,%s}" % i for i in pairs] s = ",".join (strings) I'm also not particularly happy about the choice of "it" as a variable name. The "izip (it, it)" construct makes me think of Dr. Evil :-) > I find Peter's original form easy to read -- if you understand how "izip(it, > it)" works (which is a very simple and elegant way to iterate over (it[n], > it[n+1]) pairs), the rest is very clear. It's not the izip bit that bothers me in the original, it's the deeply nested construct of ",".join(["{%s,%s}" % i for i in izip(it, it)]) There's too much going on in that one line to get your head around easily. I suppose people who are really into functional programming might find it understandable, but I find it rather obtuse.

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Re: transforming a list into a string
by bokr＠oz.net Aug. 1, 2004

Aug. 1, 2004

On Sun, 1 Aug 2004 11:00:32 +1000, Andrew Bennetts <andrew-pythonlist(a)puzzling.org> wrote: >On Sat, Jul 31, 2004 at 08:43:52PM -0400, Roy Smith wrote: >> Tim Peters <tim.peters(a)gmail.com> wrote: >> > Note that Peter Otten previously posted a lovely O(N) >> > solution in this thread, although it may be too clever for some >> > tastes: >> > >> > >>> from itertools import izip >> > >>> items = ['1','2','7','8','12','13'] >> > >>> it = iter(items) >> > >>> ",".join(["{%s,%s}" % i for i in izip(it, it)]) >> > '{1,2},{7,8},{12,13}' >> >> Personally, I'm not a big fan of clever one-liners. They never seem >> like such a good idea 6 months from now when you're trying to figure out >> what you meant when you wrote it 6 months ago. > >It's a two-liner, not a one-liner (although it could be made into a >one-liner with enough contortions...). > Assuming items definition doesn't count in the line count, >>> items = ['1','2','7','8','12','13'] then one line seems to do it, not that obscurely (depending on your glasses ;-) >>> ",".join(["{%s,%s}"%(n(),n()) for n in [iter(items).next] for i in xrange(0,len(items),2)]) '{1,2},{7,8},{12,13}' >The only other way I could see to expand this solution would be to write it >as: > it = iter(items) > pairs = izip(it, it) > s = ",".join(["{%s,%s}" % i for i in pairs]) > >I don't know if three-liners meet your threshold for verbosity ;) > >Well, you could write it as: > > pairs = [] > it = iter(items): > while True: > try: > pair = it.next(), it.next() > except StopIteration: > break > pairs.append(pair) > s = ",".join(["{%s,%s}" % i for i in pairs]) > >But at that point, the scaffolding is large enough that it obscures the >purpose -- I definitely find this harder to read than the two-liner. > >I find Peter's original form easy to read -- if you understand how "izip(it, >it)" works (which is a very simple and elegant way to iterate over (it[n], >it[n+1]) pairs), the rest is very clear. Agreed. Regards, Bengt Richter

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Python/ADSI Problem
by Ondrej Krajicek Aug. 1, 2004

Aug. 1, 2004

Hello, I have problem with the following code: rootdse = ldap.OpenDSObject(ROOTDSE_URL, USER_NAME, PASSWORD, opts) nc = rootdse.Get("defaultNamingContext") uri = "LDAP://%s/%s" % (SERVER_NAME, nc) dc = ldap.OpenDSObject(uri, USER_NAME, PASSWORD, opts) cnUsers = dc.GetObject("top", "Users") ## <-- exception is thrown here The last line throws an exception: com_error: (-2147352567, 'Exception occurred.', (0, None, None, None, 0, -2147016654), None) I've tried several variants, such as: GetObject(None, "Users"), GetObject("", "CN=Users"), GetObject(u"", u"CN=Users") with no success. Similar code in C++ works perfectly, i.e. the binding URLs, flags, etc. seem to be correct. Anything obvious I've missed? Thanks, Ondra -- ____________________________\\--//_________________________ Ondrej Krajicek \\// krajicek(a)ics.muni.cz Institute of Computer Science,||Masaryk University Brno, CR _____________________________//\\__________________________

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Re: IronPython-0.6 is now available!
by Valentino Volonghi aka Dialtone Aug. 1, 2004

Aug. 1, 2004

On Sat, 31 Jul 2004 13:37:35 +1000, Derek Thomson wrote: > So, why can't it just be basically: > > object.echo("hello network") > > ... as it is in CORBA and (other) XML-RPC and SOAP toolkits I've used. I don't think that calling: object.echo("hello network") instead of object.callRemote('echo', 'hello network') is making any difference at all... Actually the CORBA author is evalutaing twisted for his next needs (IIRC). Add this to the fact that doing callRemote() you are not moving any objects around, Perspective Broker let's you copy objects from the remote side to the client side and then you would be able to call object.echo('hello network') for instance. > I also have a problem with the insistence on the use of asynchronous > callbacks. In order to use the result of the RPC call later in the > main flow of my code, I have to somehow block in the main thread for > the the result to be returned from the server via the callback - this > is something that can be done for me, and is handled simply and > transparently in other RPC toolkits/mechanisms I've used. Clearly you do not know deferreds. Twisted won't wait for your response blocking the whole thread. It will just send the request and when the response comes back it will call your code for you. > I'll try to characterize this with a simple example. How would I write > something like this, where I have three distributed objects: > > i = an_object.get_value() > j = another_object.get_value() > k = yet_another_object.combine(i, j) > > ... and now finally use "k" in my code? You will use it in a callback. Obviously if you don't like callbacks you won't like twisted, but this doesn't make RPC with twisted primitive. I would say that you simply don't like the way you write code with twisted. > I could be missing something, but isn't that going to turn into a mess > of dependant callbacks in Twisted? Aren't I going to have to write a > whole lot of code that blocks until the results come back? I don't > mean this as a challenge or a judgement anything, I'd honestly like to > know - I would like to look further into Twisted but was pretty much > put off by this issue right from the start. Code won't block. You should read how deferreds work (note: they are not making your blocking code into non-blocking code, but they will be waiting in the background for an answer to a request, without blocking everything). BTW Twisted provides 2 different ways of making you blocking code non-blocking. You can use deferToThread, if you have a very long atomic operation (like querying a remote database), or you can divide your very-big-function into many different steps and call each other with reactor.callLater(0, nextStep) Which makes the call happen the next cicle in the reactor (so to allow the reactor to handle some requests in the meantime). Usually for third party modules with blocking logic the most used choice is deferToThread. But I suggest you reading the documentation from www.twistedmatrix.com which is a lot more helpful. HTH -- Valentino Volonghi aka Dialtone Linux User #310274, Proud Gentoo User Blog: http://vvolonghi.blogspot.com Home Page: http://xoomer.virgilio.it/dialtone/

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Re: Returning another instance from constructor
by Edward Diener Aug. 1, 2004

Aug. 1, 2004

Robert Brewer wrote: > Edward Diener wrote: >> ...I can find no documentation in the Python 2.3 docs >> for __new__ . Can you point me to it ? > > Start with http://www.python.org/2.2.3/descrintro.html Thanks. I do think the information about new style classes should be part of the Python distributed documentation. Any reason why it has not been since it is now part of the language, or did I miss it somewhere in the official distribution >

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Get SystemDrive variable
by JY Doyon Aug. 1, 2004

Aug. 1, 2004

I'm writing a script that copies all information from the "Documents and Settings" folder for backup purposes. My problem is that some machines have the OS installed on a different drive than C:\. Is there any way to get the environment variable "SystemDrive" with python? Thanks for the help

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