🌐 Mailman 3 July 2000 - Python-list - python.org

writing (Gnu)MAKE in Python
by John Schmitt Aug. 14, 2000

Aug. 14, 2000

Hi. I'd love to take the diversion of writing Make using Python. The things that are keeping me from doing this are, in order: - I'm not completely convinced that doing this is a good thing - my employer has not asked me to, and I doubt they would see the value in it that I do - Make is big and complicated and reproducing all the functionality that we need (complete with quirks and bugs) would be time-consuming - if I couldn't demonstrate its value immediately the work would not be appreciated, especially since we have many other projects worthy of my time The benefits as I see them (in no order): - provide a Make that really, really works - Make would work the same everywhere! wouldn't that be great?! - not only would Make work the same way everywhere, it would take care of foreslash and backslash differences too! - Make bugs would be easier to fix - new features would be much easier to add - if I got it into our tool set, just maybe, Python will be accepted as a (preferred?:-) development tool - if I did it, it would be my opportunity to learn Python and to learn Make fairly well - did I mention portability? In a smaller way, I would like to have Bash, sed, and grep as Python programs rather than compiled C. Anyone volunteering? :-) John

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I have some problem about IDLE, help me...
by Pi Aug. 10, 2000

Aug. 10, 2000

I install Python by Debian Pakage... python excute well... but IDLE does not... if I type "idle" I got below message... Traceback (innermost last): File "/usr/bin/idle", line 3, in ? PyShell.main() File "/usr/lib/idle/PyShell.py", line 612, in main fixwordbreaks(root) File "/usr/lib/idle/editorWindow.py", line 606, in fixwordbreaks tk.call('tcl_wordBreakAfter', 'a b', 0) # make sure word.tcl is loaded TclError: extra characters after close-quote I can't see what is problem... It seems that fixwordbreaks() are source of problem... but I don't know what function is fixwordbreaks()... I excuted idle manually withbout script file... but I got same error message... If you know about this error message, Plz help me... If you know how to clear this problem, send me mail plz... leejongsoopekr(a)yahoo.com

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Type checking in python?
by Matthew Cline Aug. 8, 2000

Aug. 8, 2000

It would be nice if I could do something like: def my_func(int foo, list bar, Quux quux): ... rather than def my_func(foo, bar, quux): if not isinstance(quux, Quux): raise RuntimeError("param 'quux' must be of class 'Quux'") Is there any plans on doing this for Python 3000? Or will something like this never be a part of Python?

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Profiler
by Rikard Bosnjakovic Aug. 7, 2000

Aug. 7, 2000

I'm using the profiler-module and it works okay. But now I'm interested in checking how many bytes memory different parts of my script allocates, especially my deep-nested and huge dictionaries. Is there a way/tool/whatever for this purpose? -- Rikard Bosnjakovic - http://a214.ryd.student.liu.se Anyone sending unwanted advertising e-mail to my address will be charged $25 for network traffic and computing time. By extracting my address from this message or its header, you agree to these terms.

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let my widgets use pack/grid/place
by Keith Murphy Aug. 7, 2000

Aug. 7, 2000

how do i let widgets i've created use pack/grid/place? i.e. ... mywidget('schweet') mywidget.pack() ... thanks, -->keith Sent via Deja.com http://www.deja.com/ Before you buy.

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Newbie DATA STRUCTURES Question.
by gbp Aug. 6, 2000

Aug. 6, 2000

Hi all, I have experience with Perl but non with Python. I need to write a script to read a large text file into a structured format. In Perl one can create a list of records using something like pointers. So really you have a list of pointers-- each one pointing to an anonymous record. Each record is some data from a line in the file. Since I learned data structures in languages with pointers (C, pascal) I'm stuck. How does one go about constructing a list of records in python? My python is still pretty weak. I understand how the lists work (a lot like Perl). I understand that you can use objects as records. I don't really get the full OOP though. I guess that you can't make record anonymous in python? Is that right? Can you have pointers? When I was learning Perl I found a manual page on this. Couldn't find a example for Python. Hope that doesn't mean it can't be done. Any hints are welcome!! (reply to email and group) Thanks.

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The State of Python
by Guido van Rossum Aug. 5, 2000

Aug. 5, 2000

I've placed the slides of my talk at the O'Reilly Open Source Convention on-line at our BeOpen PythonLabs website: http://www.pythonlabs.com/talks.html We're also very close to announcing news regarding a new Python license, Python 1.6 and 2.0 release schedules, and a transition of the python.org website to hosting by VA Linux. The announcement is waiting for final negotiations about GPL compatibility of the new license; BeOpen's CTO, Bob Weiner, is confident that the issue will be resolved one way or another by Friday. A preview of what we will announce: - A new license for Python 1.6 and later: the "CNRI Open Source License", approved by the Open Source Initiative; - Release plans for Python 1.6: the last CNRI release, to be issued with help from BeOpen; - Release plans for Python 2.0: the first release to be issued by BeOpen; - A transition for the python.org website: it will be hosted by VA Linux (home of SourceForge), under supervision of the Python Consortium and myself, maintained by the Python community. Please hold your breath a little longer! A re-release of JPython using the CNRI Open Source License is possible a little later, pending further negotiations with CNRI. --Guido van Rossum (home page: http://www.pythonlabs.com/~guido/)

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Discussion: Introducing new operators for matrix computation
by hzhu＠knowledgetrack.com Aug. 5, 2000

Aug. 5, 2000

We are at a crucial juncture concerning introduction of new operators into Python for matrix computation, 1. Experiences with Matlab show that different operators for matrix and elementwise operators are very important 2. It is difficult to add .* and ./ as . is already a valid token. It seems that next candidate on the standard keyboard is @. 3. Gregory Lielens has just implemented a patch that could parse additional operators containing @ a@b is equivalent to a*b, overloaded using __mmul__ and __rmmul__ a@/b a/b __mrdiv__ and __rmrdiv__ a/@b b/a __mldiv__ and __rmldiv__ a@@b a**b __mpow__ and __rmpow__ He indicates similar constructions can be added easily. We intend to add these operators together with Thomas Wouters's augmented assignment operators (+=,*=, etc) to MatPy, but before that several decisions need to be made. First, the main choices: 1. Use a*b as matrix mul, and a@*b as elementwise mul. Pros: - Consistent with Matlab. - Consistent with current MatPy. - Convenient for matrix computations. Cons: - Inconsistent with NumPy - How to differentiate left and right div (matlab a\b and a/b)? 2. Use a@*b as matrix mul, and a*b as elementwise mul. Pros: - Consistent with NumPy - Can use a@/b and a/@b as matlab a/b and a\b. - Can use a@b as inner product so that a@b works irrespective of whether a and b are row or col operators. Cons: - Inconsistent with current MatPy. Need great effort to switch. - Using two symbol operator for matrix mul is cumbersome for long formulas. - It kind of looks ugly. 3. Use a@b as matrix mul, and a*b as elementwise mul. This has most of the pros and cons of choice 2, except Pros: - Single symbol operators for matrix mul and element mul. Cons: - Can't use a@b as inner product. Just to add to the agony, here are a few contrary views: 1. Consistency with Matlab is not necessarily good. In Matlab operators default to matrix (cf * and .*) but functions default to elementwise (cf exp and expm). In Python ** is defined by __pow__. Should it be consistent with pow the function or ** the operator? 2. Consistency with NumPy is not necessarily good. Currently one can use MatPy and NumPy at the same time. a*b will be matrixwise for MatPy and elementwise for NumPy. This is convenient when each usage is dominant in some part of a program. Removing this difference and MatPy will lose a lot of appeal when it is needed. 3. Although it is relatively difficult to switch the usage in MatPy, it is still a good time if we deem this to be A Good Thing. When the status is changed to beta from alpha it would be next to impossible to switch. To throw you completely off the track, here is one additional feature request that would great please mathematicians and greatly annoy computer scientists: Use ^ and @^ for matrix power. Currently ^ is defined as xor which is of sufficiently low level that is unlikely to occur with matrix computations. Note that this is not in our plan right now. One other thing that will be of great efficiency value (whenver somebody comes forward to do it) is to parse := as assignment. This way we can let a=b be simple reference assignment without creating a new Matrix object. The implementors of both previous patches have cautioned that Guido is unlikely to adopt the patch for the .* or @* operators. But I'm quite confident that he can be persuaded. There is a large number of users of Matlab and Octave (maybe even more than users of Python), and there is no fundamental reason they cannot use Python for doing the same thing, provided that we are allowed to add this little additional operator. :-) What other incentives are needed to persuade Guido? Here's a quote from Gregory, > they make a huge difference in readability of code dealing with linear > algebra, in particular when using small matrices. Such operators explain > partly the popularity of Matlab-like tools, imho. I can argue that linear algebra is very important for Python, perhaps even more important than complex numbers, but this is off topic. So all your comments, suggestions and flames a invited. I just have a small request: As this is getting too long, please reply separately to different parts of this article, so that the discussion threads remain manageable. -- Huaiyu Zhu hzhu(a)users.sourceforge.net Matrix for Python Project http://MatPy.sourceforge.net

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iterating over lines in a file
by nobody Aug. 5, 2000

Aug. 5, 2000

assume i want to iterate a block of code over every line in a text file, and that i don't want to snarf the whole thing into memory for fear of coredumps or whatever. in perl (and many others) there is a simple, common idiom: while (line = <FILE>) { block; } this doesn't seem to have a simple, direct analog in python. searching around on the web i found a solution at faqts.com (though this newbie might like to see it explained, but whatever works): class Reader: def __init__(self, source): self.source = source def readline(self): line = self.source.readline() self.line = line return line # may be empty, thus false file = Reader(open("filename")) # i might have got this worng...? while (file.readline()): line = file.line now, this seems to me like an awful lot of typing just to get around the fact that assignments in python do not seem to be expressions returning the value assigned. since that is thus in several other languages, and since it gives rise to several common idioms of this type, i can only assume that there must be some good reason for breaking this pattern in python; i just can't see what it could possibly be. could somebody enlighten me, please? and is there any easier way to iterate over lines in a file without resorting to ugly break statements?

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Text UI Curses sample code
by Terry Aug. 5, 2000

Aug. 5, 2000

I have no experience with a text based UI and would appreciate all the advice and sample code I can get. Thanx in advance Terry

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