🌐 Mailman 3 August 2021 - Python-list - python.org

Re: some problems for an introductory python test
by Hope Rouselle Aug. 14, 2021

Aug. 14, 2021

Chris Angelico <rosuav(a)gmail.com> writes: > On Thu, Aug 12, 2021 at 9:23 AM Dennis Lee Bieber <wlfraed(a)ix.netcom.com> wrote: [...] >> I was spoiled by the Amiga variant of REXX. Most current >> implementations (well, Regina is the only one I've looked at) can just pass >> command to the default shell. The Amiga version took advantage of Intuition >> Message Ports (OS supported IPC). That allowed it to "address >> <application>" any application that defined an ARexx port, allowing ARexx >> to be used as a scripting language for that application (and with multiple >> applications, one could easily fetch data from app1 and feed it to app2). >> ARexx did not, to my memory, implement arbitrary precision math. > > The same functionality was available in OS/2, but not heavily used. > You could 'address cmd commandname' to force something to be > interpreted as a shell command, but that was about it. However, I > built a MUD that used REXX as its scripting language, and the default > destination was sending text back to the person who sent the command; > and you could, of course, still 'address cmd' to run a shell command. > >> I've not seen anything equivalent in my light perusal of the Win32 API >> (the various guide books aren't layed out in any way to be a reference), >> and Linux seems to use UNIX sockets for IPC... No way to search for a >> connection point by name... > > Win32 doesn't really have it. Unix sockets are kinda there but you > identify something by a path to the socket, not the name of the > application. But I think dbus is probably the closest to what you're > thinking of. Win32 offers some APIs that sound like it could be what you guys are talking about here that I'm not too clear what it is. There are some shared memory you can reference by name, so it's as easy to use: both applications invoke a procedure with a string-argument and exchange information that way. (And Win32 does support named pipes as well.) I mean I'm sure you know it all better than I do. (Perhaps I'm too clueless here.) I could look up the Win32 APIs I'm thinking of if that would clarify things.

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Empty list as a default param - the problem, and my suggested solution
by guruyaya Aug. 14, 2021

Aug. 14, 2021

I am fairly sure all of us know about this python quirk: >>> def no_new_func(a=[]): ... a.append('new') ... return a >>> no_new_func() ['new'] >>> no_new_func() ['new', 'new'] >>> For some time I was bothered about that there's no elegant way to use empty list or dict as a default parameter. While this can be solved like this: >>> def no_new_func(a=None): ... if a == None: a = [] ... a.append('new') ... return a I have to say I find this solution very far from the spirit of python. Kinda ugly, and not explicit. So I've decided to try and create a new module, that will try and make, what I think, is a more beautiful and explicit: >>> from new import NEW >>> @NEW.parse ... def new_func(a=NEW.new([])): ... a.append('new appended') ... return a ... >>> new_func() ['new appended'] >>> new_func() ['new appended'] I'd like to hear your thoughts on my solution and code. You can find and give your feedback in this project https://github.com/guruyaya/new If I see that people like this, I will upload it to pip. I'm not fully sure about the name I choose (I thought about the "new" keyword used in JAVA, not sure it applies here as well) Thanks in advance for your feedback Yair

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Recoding Categorical to Numerical
by John Griner Aug. 14, 2021

Aug. 14, 2021

thanks <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> <#m_4567368322047287300_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

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Recoding Categorical to Numerical
by John Griner Aug. 14, 2021

Aug. 14, 2021

Hello, and thanks in advance, I am trying to recode categorical variable to numeric. Despite using lambda, If else, dummy-recoding, and so forth, what I get is from ONE column that has 4 variables (City, Town, Suburb, Rural), I get FOUR columns: localeDummy_City localeDummy_Town localeDummy_Suburb localeDummy_Rural locale_recode with the corresponding numeric variable. What I want is the recode to have ONE column that has the numeric conversion. For instance: local_recode 2 4 4 6 2 8 6 2 8 2 2 4 6 4 8 and so forth, where I have set City to 2, and Town to 4, etc. Again, thanks, John loca <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

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Can't get rid of old version of python
by Ciarán Ó Duibhín Aug. 13, 2021

Aug. 13, 2021

Hi, On Windows 10, I uninstalled all previous versions of Python and installed v3.9.6. When I use the start menu option Python 3.9 (64-bit), I get the prompt "Python 3.9.6" as expected. The same happens when I type "py" at the DOS prompt. But when I type "python" at the DOS prompt, I get "Python 3.8.10". I don't understand this, as I uninstalled old versions, and I do not see a DOS environment variable called "python" anywhere. The real problem comes when I install a package, e.g. germalemma. Python 3.8.10 can use it, but Python 3.9.6 can't find it. I notice that "site-packages" containing germalemma and its dependencies is located in ...Packages\PythonSoftwareFoundationPython.3.8.qbz5n2kfra8p0\LocalCache\local-packages\Python3.8 Also there is a load of python 3.8 stuff at C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.8_3.8.2800.0_x64__qbz5n2kfra8p0 which directory is virtually inaccessible from Windows but can be listed in DOS. How can I get rid of Python 3.8.10 , and install my packages to 3.9.6? Ciarán Ó Duibhín

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Re: on slices, negative indices, which are the equivalent procedures?
by Michael F. Stemper Aug. 13, 2021

Aug. 13, 2021

On 11/08/2021 20.17, dn wrote: > > I've been trying to remember if we had negative-steps in FORTRAN > do-loops My text for Fortran 77 (the last version that I ever used) says that negative increments are supported. Ref: _FORTRAN 77: Language and Style_; Michael J. Merchant; Wadsworth Publishing Company; (c) 1981; Page 125 It also says that zero increments are not supported. (Whew!) -- Michael F. Stemper 87.3% of all statistics are made up by the person giving them.

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pip doesn't work
by Ridit Aug. 13, 2021

Aug. 13, 2021

So, whoever gets this, when I try to download packages using pip, it shows errors saying "'pip' is not recognized as an internal or external command, operable program or batch file." Is there a way to solve this? I tried modifying, even repairing three times, but still it doesn't work. If you have a solution, thank you.

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Re: some problems for an introductory python test
by Greg Ewing Aug. 12, 2021

Aug. 12, 2021

On 13/08/21 5:52 am, Grant Edwards wrote: > I think what he's talking about is allowing the user to attach > arbitrary _metadata_ to the file ... IOW, something similar to the > "resource fork" that MacOS used to have. The resource fork was used for more than just metadata, it was often the entire contents of the file. Applications had all the code in there, for example -- the data fork of an application was usually empty. -- Greg

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Re: some problems for an introductory python test
by Greg Ewing Aug. 12, 2021

Aug. 12, 2021

On 13/08/21 11:42 am, Cameron Simpson wrote: > 2: It took me a while to see, but this is a type annotiation. Interestingly, it seems to be parsed as a form of assignment with a missing RHS. >>> from ast import parse, dump >>> dump(parse("if0: print('yes!')")) "Module(body=[AnnAssign(target=Name(id='if0', ctx=Store()), annotation=Call(func=Name(id='print', ctx=Load()), args=[Constant(value='yes!', kind=None)], keywords=[]), value=None, simple=1)], type_ignores=[])" "An annotated assignment without the assignment? Eeuurgh!" -- Greg

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Re: some problems for an introductory python test
by Hope Rouselle Aug. 12, 2021

Aug. 12, 2021

Chris Angelico <rosuav(a)gmail.com> writes: [...] >> > [1] And boy oh boy was that good fun. The OS/2 Presentation Manager >> > had a wealth of power available. Good times, sad that's history now. >> >> I know OS/2 only by name. I never had the pleasure of using it. In >> fact, I don't even know how it looks. I must be a little younger than >> you are. But not too younger because I kinda remember its name. Was it >> a system that might have thought of competing against Microsoft Windows? >> :-) That's what my memory tells me about it. > > History lesson! > > Once upon a time, IBM and Microsoft looked at what Intel was > producing, and went, hey, we need to design an operating system that > can take advantage of the fancy features of this 80286 thing. So they > collaborate on this plan to make a 16-bit protected mode OS. > Unfortunately, things didn't work out too well, partly because this > was when Microsoft was at its most monopolistic, and they ended up > parting company. IBM continued to make OS/2, but Microsoft took their > part of the code and made Windows NT out of it. How is it possible that Microsoft would take part of the code of OS/2? Did IBM just hand it to them? > (Aside: Windows NT's 16-bit applications and OS/2's 16-bit > applications were actually identical and compatible. Unfortunately, > Win32 introduced a very new API, so as soon as everyone moved to > 32-bit everything, the schism became problematic. But it was actually > possible to package up a single .EXE file with a 16-bit MS-DOS loader, > a Win32 loader, and an OS/2 32-bit loader, all happily coexisting. Beautiful. :-) So if all libraries were around in each system, they had perfect compatibility? > In the latter half of the 1990s, Windows came in three broad flavours: > the 16-bit Windows 3.x line, which ran purely on top of DOS; the > 32-bit Windows 95 line, which was the "home" OS and had to be heavily > compatible with Windows 3, but still doing more things; and the > Windows NT line, which was aimed at businesses. OS/2 was a viable > option for businesses, but almost nobody took it seriously as a home > OS. And Microsoft was using its marketing machine to push Windows > fairly hard, so most people went that way. > > OS/2 had all kinds of amazing features (for its time). The default > file system, HPFS ("High Performance File System"... IBM was good at > many things, but imaginative naming wasn't one of them), did a > spectacular job of maintaining reliability and performance on the > ever-growing hard disks of the time. Yes, it coped remarkably well, > even on *gigantic* drives that could carry, ooh, an entire gigabyte of > data! I'm not kidding! We even had a drive that had TWO gigabytes of > space, and HPFS managed it beautifully! Plus, it had this fancy > concept of "extended attributes"; on older systems (like MS-DOS's > "FAT" family), a file might be Read-Only, Hidden, a System file, or > needing to be Archived, and that was it - but on HPFS, you could > attach arbitrary data like "File type: DeScribe Word Processor" or > "Double click action: Run CASMake.cmd". This allowed the GUI to store > all kinds of information *on the file itself* instead of needing > hidden files (or, in Windows' case, the registry) to track that kind > of thing. Yeah, that's kinda nice. Isn't that a UNIX design? A file is a sequence of bytes? Users decide what to put in them? So OS/2 was taking advantage of that to integrate it well with the system. Windows was doing the same, but integrating the system with files in odd ways --- such as a registry record to inform the system which programs open which files? (That does sound more messy.) UNIX's execve() is able to read the first line of an executable and invoke its interpreter. I guess OS/2 was doing precisely that in a different way? > The default command interpreter and shell on OS/2 was fairly primitive > by today's standards, and was highly compatible with the MS-DOS one, > but it also had the ability to run REXX scripts. REXX was *way* ahead > of its time. It's a shell language but remarkably well suited to > building GUIs and other tools (seriously, can you imagine designing a > GUI entirely in a bash script??). I cannot imagine. I always wondered what REXX was about --- I saw programs sometimes written in some website whose name is something like Rosetta Code. REXX looked so weird. (``Who would program in that?'') But I see now there is a context to it. > It had features that we'd consider fairly normal or even primitive by > Python's standards, but back then, Python was extremely new and didn't > really have very much mindshare. REXX offered arbitrary-precision > arithmetic, good databasing support, a solid C API that made it easy > to extend, integrations with a variety of other systems... this was > good stuff for its day. (REXX is still around, but these days, I'd > rather use Python.) Yeah, REXX looks horrible at first. But arbitrary-precision is definitely very attractive. I never liked to deal with floating-point. > I mentioned the Presentation Manager, because it was one of the best > parts of running OS/2. The kernel was decent, but it was the graphical > shell that was the real pleasure to work with. Probably the most > notable feature, by today's standards, was that it had a single input > queue. If you press a series of keys, they'd go into a global queue, > and the application that has focus would get the first one. When that > key has been handled, the application that has focus would get the > next key from the queue. This means that, if the response to a > keystroke is to change focus, then *even in a slow and lagged out > system*, subsequent keys WOULD be sent to the new target window. That > was AWESOME, and I really miss it. Except that I also don't. Because > if a single application is having issues, now your entire keyboard and > mouse is locked up... which kinda slightly sucks. Good luck resolving > that problem. (We had some neat tools like WatchCat that could get > around the single input queue via interrupt signals, and regain > control. But it was still problematic.) Wow, I kinda feel the same as you here. I think this justifies perhaps using a hardware solution. (Crazy idea?! Lol.) Maybe machine and OS could have a desktop-version that would have a hardware that could effectively be like a second keyboard --- a button. So our keywords would have a button that we press it, we could interrupt the OS to handle such lock-up more gracefully. I suppose this is expensive, complex and so on. But at the same time, it could be worth it. > So, yeah. It was spectacular in its day.... but it kinda got left > behind as the world moved on. These days, instead of running REXX code > on OS/2 in a system that uses eight-bit text for most things, I use > Python on Linux and full Unicode. But OS/2 was an important part of > history, both my own personal journey, and the history of the world of > PCs. Very nice. Thanks a lot for sharing. I care a lot about such histories. In fact, if you could point out from the top of your head the best reference on the facts you mentioned here, I would love to write it down for future reference. (You probably read books that perhaps explained how the queue of windows messages worked et cetera.) Thank you!

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