🌐 Mailman 3 August 2007 - Python-list - python.org

Extending doctest
by Neil Cerutti Aug. 1, 2007

Aug. 1, 2007

One of my current tests looks like this (the program is an interpreter for a scheme-like language): >>> result = parse_op('(with (b (newbox 5))' ... ' (seqn (setbox b 1)' ... ' (setbox b 2)' ... ' (setbox b 3)' ... ' b))').interp(EmptyEnv(), EmptyStore()) >>> result #doctest: +ELLIPSIS (<Box ...>, ~...: <Num 3> ~) >>> result[0].location == result[1].location True The memrory location that the box refers to must match the actual location in storage. Currently, the doctest stinks because it depends on internal details of my implementation. Is there a doctest feature that will allow me to stipulate that one thing in a result is arbitrary, but identical to another thing in that result? -- Neil Cerutti Trespassers will be prosecuted to the full extent of the law --sign at Sisters of Mercy Nunnery

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Where do they tech Python officialy ?
by NicolasG Aug. 1, 2007

Aug. 1, 2007

Hi, I want to be a professional python programmer, unfortunately I'm working on technical support and don't have the time/patience to start making projects my self. I tried to apply to some Python positions but unfortunately sometimes to work as a programmer is really hard in this world, every employee requires professional experience and you can't really start as a beginner.. I'm planning to save some money and attend a course in any of the universities that teach hard core Python. Does some one have any suggestions on which University to attend ? Alternatives solutions are welcome.. Regards, Nicolas G.

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Re: http client module
by stefano Aug. 1, 2007

Aug. 1, 2007

On 31 jul, 23:07, Steve Holden <st...(a)holdenweb.com> wrote: > stefano wrote: > > Hello i'm looking for a http client for python i found this one call > > httplib2 > > >http://64.233.169.104/search?q=cache:0jJWNfodK6gJ:bitworking.org/proj... > > > but is too old > > Look at urllib and urllib2 in the standard library. If they don't give > you what you want, think about using mechanize and ClientForm, or > possible beautifulsoup, all of which Google should be able to find for you. > > regards > Steve > -- > Steve Holden +1 571 484 6266 +1 800 494 3119 > Holden Web LLC/Ltd http://www.holdenweb.com > Skype: holdenweb http://del.icio.us/steve.holden > --------------- Asciimercial ------------------ > Get on the web: Blog, lens and tag the Internet > Many services currently offer free registration > ----------- Thank You for Reading ------------- thanks

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wxPython version question
by The Max Aug. 1, 2007

Aug. 1, 2007

Hi at all Hi have need of testing the version of wxPython in use .... at the moment I use wxversion, but I don't can find a method for testing version like this: if versionOfWX() <= 2.8: or if versionOfWX() >= 2.8: ( versioneOfWX is a pseudo-function create for this example ) Someone know a solution for this ? Thanks and sorry for my orrible english

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Re: zip() function troubles
by Paul Rubin Aug. 1, 2007

Aug. 1, 2007

"Chris Mellon" <arkanes(a)gmail.com> writes: > Better hand in your computer, then. You're never going to find a > situation where the environment won't affect the running time of your > algorithms. The environment may affect the running time by an additive or linear multiplicative constant but it should never turn an O(n) algorithm into an O(n**2) one. > For the record, the python GC is generational. This is a case of a > default heuristic giving pathological behavior in a corner case, not > anything broken about the design of the python GC. No, it is broken, per discussion on a comp.compilers/comp.lang.functional thread this week. The notion of using a generational collector was to collect less and less frequently for older and older generations (e.g. doubling the amount of allocation between generations) but the usual solution is apparently to increase the heap size by some multiplicative factor when GC fails to free enough memory.

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Plain old SAX and minidom useable? But how then?
by Dobedani Aug. 1, 2007

Aug. 1, 2007

Dear All, I guess I don't know where to look for the right information. I hope you guys can help me on the way. I want to retrieve a string from an XML-file. If Python were to have XPath available, my problem would be solved. The xquery string would be enough and I have already obtained that the string. The problem is that I cannot use any add-on - like xmllib, sax2 or elementtree - as my customers only have the so-called stock Python install - i.e. version 2.4.1. I've seen some posts from 2½ years ago by Nelson Minar and also by Uche Ogbuji who wrote: "Nelson says: There's the stock Python install, which barely does anything [for XML]. That's overstated. Plain old SAX and minidom may not be ideal, but they're useable." Please: where then can I find examples of such use? If I cannot use xpath, I would not mind to browse a bit - e.g. using functions like getElementByTag() but I don't even know how to use those. TIA Kind regards, Dobedani

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Re: access the name of my method inside it
by Marc 'BlackJack' Rintsch Aug. 1, 2007

Aug. 1, 2007

On Wed, 01 Aug 2007 07:01:42 -0400, Steve Holden wrote: > Marc 'BlackJack' Rintsch wrote: >> On Wed, 01 Aug 2007 09:06:42 +0000, james_027 wrote: >> >>> for example I have this method >>> >>> def my_method(): >>> # do something >>> >>> # how do I get the name of this method which is my_method here? >> >> Why do you need this? There are ways but those are not really good for >> production code. >> > Maybe he wants to write a recursive method? > > Once way is to call self.__calss__.mymethod(self). Ugly, isn't it? Ugly yes, unnecessary convoluted yes, solution no. You typed `my_method` in the source. The OP wants to know how to avoid that. > >>> class p: > ... def mymethod(self, n): > ... if n <= 1: > ... return 1 > ... else: > ... return n * self.__class__.mymethod(self, n-1) Why not simply ``self.mymethod(n - 1)`` instead!? Ciao, Marc 'BlackJack' Rintsch

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Re: Python end of file marker similar to perl's __END__
by Stargaming Aug. 1, 2007

Aug. 1, 2007

On Wed, 01 Aug 2007 06:56:36 -0400, Steve Holden wrote: > Stargaming wrote: >> On Wed, 01 Aug 2007 05:44:21 +0000, Michele Simionato wrote: >> >>> On Aug 1, 5:53 am, beginner <zyzhu2...(a)gmail.com> wrote: >>>> Hi All, >>>> >>>> This is just a very simple question about a python trick. >>>> >>>> In perl, I can write __END__ in a file and the perl interpreter will >>>> ignore everything below that line. This is very handy when testing my >>>> program. Does python have something similar? >>> I wished from something like that. What you can do at the moment, is >>> to comment or triple quote the code you don't want to run. >> >> Or, if in a function body, you could insert a `return` statement. When >> in top-level code, invoking `sys.exit` (or exit/quit) can do the trick. >> A ``raise Exception`` might help, too, but could be kinda distracting >> sometimes. >> >> So, there is no general purpose solution as perl has it (I guess that >> __END__ works everywhere at least), rather different solutions for >> different cases. > > I think you have missed the point. A return statement or call to > sys.exit() doesn't remove the requirement that the rest ofthe source > file be legal Python. In a Perl program you can put anything you like > after __END__. > > regards > Steve That was my point actually. No, there is no such general purpose solution as in perl, but if he just wanted to quit execution (to, eg., not commit changes to his database), this would be the way to go. Multiline strings are the other way to include (nearly) arbitrary data.

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Re: Reload after an exception, not possible ?
by Stef Mientki Aug. 1, 2007

Aug. 1, 2007

Steve Holden wrote: > Stef Mientki wrote: >> hello, >> >> I've a graphical application (wxPython), >> where the code in the main GUI loop is given below. >> >> >> 1 JAL_Loaded = False >> 2 while len(App_Running) > 0: >> 3 if JALsPy_globals.State == SS_Run: >> 4 try: >> 5 if JAL_Loaded: >> 6 reload ( JAL_simulation_file ) >> 7 else: >> 8 JAL_Loaded = True >> 9 import JAL_simulation_file >> 10 except JALsPy_globals.Reload_Exception: >> 11 JALsPy_globals.State = SS_Halt >> >> >> The first time the while loop is entered, >> JAL_Loaded is False (line 1), >> and when I press some button, >> the code will enter at line 8, >> importing a module, that has executable code with an infinite loop. >> >> To exit this infinite loop, an exception is generated (by a button >> press), >> and program comes back in the above while-loop line (10,11,2). >> >> So far so good. >> >> Then I change the code in the imported file, >> and when I start the engine again, >> the flag JAL_Loaded is True, so I don't import, >> but I reload the file. >> >> Now I get the next exception >> UnboundLocalError: local variable 'JAL_simulation_file' referenced >> before assignment >> >> So obviously I can't reload but have to do an import again >> (which makes the code much simpler ;-) >> but I don't understand why the reload raises an exception ???? >> > You have an assignment to JAL_simulation_file elsewhere inside the same > function, No these are the only 2 uses of "JAL_simulation_file" in the whole project. later in the code. This means that Python will assume that it > is local to the function, but the import statement will affect the > module namespace rather than the function namespace. > > In other words, your code is roughly equivalent to what follows, with > the added complexity that the illegal reference isn't triggered until > the second iteration of a loop. > > >>> def f(): > ... print os > ... import os > ... os = "Something" > ... > >>> f() > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > File "<stdin>", line 2, in f > UnboundLocalError: local variable 'os' referenced before assignment > >>> > > The solution? Don't assign to JAL_simulation_file, and the function will > use the local instead. > The solution is much simpler, but I don't understand why the "import", which really reloads the changed code in JAL_simulation_file, works the second time :-( 2 while len(App_Running) > 0: 3 if JALsPy_globals.State == SS_Run: 4 try: 9 import JAL_simulation_file 10 except JALsPy_globals.Reload_Exception: 11 JALsPy_globals.State = SS_Halt cheers, Stef Mientki

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Re: Process Control Help
by Azazello Aug. 1, 2007

Aug. 1, 2007

On Jul 28, 1:40 am, "Hendrik van Rooyen" <m...(a)microcorp.co.za> wrote: > <tyle...(a)jeld-wen.com> wrote: > > > I'm attempting to start some process control using Python. I've have > > quite a bit of literature on networking, and have made some tinkering > > servers and clients for different protocols HTTP, FTP, etc... But now > > it's time for the murky web of industrial protocol. I'm looking to > > start with IO and servo controls via Ethernet. > > > Questions: > > > Is there an existing forum on this already? > > What protocols are the most python friendly? i.e. are transparent > > enough that i can create my own python driver. (or do these drivers > > exist?) > > What ethernet accesible servo and IO industrial devices have people > > had success with? > > What is it that you are trying to do? > Some of the commercial devices come with their own software, and > you may not need python or anything else. > A lot of the industrial connectivity is still RS-485 or RS-422 and not > Ethernet based - although some of the protocols, have, I think, been ported. > > If you say more, then someone can maybe help you, as there are quite a few > people on this group who seem to dabble in process control. > > - Hendrik- Hide quoted text - > > - Show quoted text We're looking to run some industrial machinery from a PC. Starting with some basic servo controls and IO port reading for something like an XYZ table (just X would be a good start!). Now there is some existing software out there for PC control but this software is, to my understanding, largely unnecessary and "black box". This "black box" creates a problem when trying to e.g. control servos and IO with the same program. And if we want to include an HMI like a touchscreen, or export the machinery's production into a RSS feed, the web of software becomes messy and slow. If we could consolidate this software into a single, non "black-box" package, we could see significant improvements in development time. Having to program 3 different devices with three different languages to control your PLC, Servos, and module X is the status quo we face, but it is quite frustrating and limited. Soo.... I need to find some ethernet friendly IO, serial would be fine but but it's a leash in many instances. I know some protocols have been ported to ethernet, but I am having extreme difficulty figuring out what these protocols entail. ModBus/TCP is the one I'd like to choose. I know that people have done this kind of software but it seems that industrial python remains a bit taboo because of proprietary issues... Ty

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