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

Eight suggestions for Python books (long)
by gvwilson＠nevex.com Feb. 5, 2000

Feb. 5, 2000

One of the most exciting things for me about the 8th Int'l Python Conference in Washington last week was the growing number of books on Python. When I had to choose a language to use in a software engineering course two years ago, I felt I had to choose Perl, because there was so much more documentation for it than for any other Open Source scripting language. Last October, I finally felt that I could switch to Python, and feedback since then has been pretty positive. I heard several people at the conference say that they were also excited and that they were thinking about doing a book. That got me thinking about what books the community really needs, and that got me thinking about the list of unwritten books that I wrote for "Doctor Dobb's Journal". I started doing book reviews for DDJ a few years ago. After a while, I decided that the best way to get the books I really wanted was to write the reviews first, and hope that someone would come along and fill in the book later. The result was posted at http://www.ercb.com/feature/feature.0012.html, and got a very (very) enthusiastic response from publishers, most of whom stay awake at night trying to figure out what we're all going to want to buy a year from now. So, here's my first cut at what books Python needs, and why. My main interests are books that will help new Python programmers be productive in a hurry, and help make Python look like a credible solution in both academia and industry. Your mileage may vary... 1. The Python Cookbook The most frequent question in my classes is, "How do I do XYZ in Python?" Most of the time, the people asking the questions know how to do what they wants in C or Perl; we need to make it easy for them to find out what the answer is in Python. The easiest way to write this book would be to go through O'Reilly's "Perl Cookbook", throw away those examples that exist only to help people get around Perl's syntax and execution model, and re-write the rest in Python. 2. Algorithms and Data Structures in Python This book complements "The Python Cookbook" by showing how classic algorithms and data structures are implemented in Python, rather than how to open a secure socket. Again, the quickest way to tackle this would be to take inspiration from books such as Orwant et al's "Mastering Algorithms with Perl", or any of Mark Weiss's DS&A books. One caution: remember that CPython and JPython manage memory differently. Try to show the best solution for each, rather than trying to accommodate weaknesses that are specific to one or the other. Also try to include more theoretical analysis of algorithm performance than Orwant et al did --- the long-term goal for this book is to be usable in a second-year DS&A course. 3. Computer Science Python Style Logo is to children's computing what C is to systems programming, and Brian Harvey's three-volume series "Computer Science Logo Style" is to Logo what Kernighan and Ritchie's "The C Programming Language" is to C. Anyone who wants to teach children to program, in any language, will find "CSLS" a rich source of ideas, and a good guide to what children (and their teachers) can actually understand. In particular, if anything is longer or harder to explain in Python than in Logo, it's a good sign that an extension library is needed... 4. Software Tools in Python Unix might not be the most widely-used operating system today, but it has certainly been the most influential. One reason for its success is the ease with which different tools can be combined, and one reason for that is that most Unix tools use a common data format: tokens separated by whitespace, terminated by newline characters. Another reason was Kernighan's book "Software Tools" (and later "Software Tools in Pascal"), which explained why and how to build small things that did one job well. The advent of XML means that there is now another universal data format that a wide variety of tools could operate on. Unlike flat text, this format is hierarchical, but the principle of connecting many tools together using pipes is still the same. That raises three questions: what are the equivalents of 'wc', 'head', 'grep', and 'sed' for tree-structured data, what language will those tools be written in, and who is going to write the best-selling book that explains all of this? As with (3) above, a lot of work would have to be done on software to make this book possible, but anyone thinking about writing usable XML filters in Python would do well to think about how to explain them before laying down any code. 5. Case Studies in User Interface Design Some philosophers distinguish between knowing that, and knowing how. The former is mostly facts, such as the airspeed of an unladen African swallow. The latter consists of techniques, like how to ride a bicycle, or how to design a user interface. Unfortunately, knowledge of the second type is hard to put into books, since every general rule has exceptions, and none of the important ideas can be given exact definitions. This book on user interfaces would try to teach the "how" by working through a series of examples. The starting point for each would be either an existing interface that needs improvement, or a set of requirements and a blank canvas. Each design would be iterated several times, or try to satisfy different constraints (e.g. hand-held vs. desktop platforms). The focus would not be on Python per se, but implicit in the book would be the message that Python facilitates rapid experimentation, prototyping, and evolution. 6. C for Python Programmers As many people have pointed out, Python is an excellent teaching language. It runs almost everywhere, is used in industry, is object-oriented, and checks for a lot of simple errors, including bad type casts, dangling pointers, and out-of-bounds array indices. If Python becomes widely used in grade schools, and if highbrow features like generic programming and type inference are added, it will start to look very attractive as a college-level language. The problem, however, is what to do with students in their second year. As a sophomore, I took two courses: one on data structures and algorithms, and one on machine architecture and assembly-language programming. The first is easy to translate into Python, but what about the second? Going from Pascal to PDP-11 assembler was bad enough; going from an interpreted, garbage-collected language to today's pipelined RISC architectures would be impossible. This book's premise would be that C has always really been a high-level assembly language, and that we should teach it to students in relation to Python as we taught assembler in relation to Pascal. It would show readers how to build a simple Python interpreter using C, and would cover pointer arithmetic and array indexing, allocating and freeing memory, garbage collection, signed vs. unsigned arithmetic, and machine-dependent data sizes. Along the way, students would be introduced to the quirks of C, including the use of preprocessor directives to handle platform-dependent code. By the time they were done, students would be ready to tackle higher-level courses in networking, operating systems, computer graphics, and other topics. They would also have learned how to structure complex software systems in layers and modules, and how to deal with a variety of real-world software engineering issues. (Note that this book would teach C, rather than C++, so that students would learn what computers really do --- C++ sweeps far too much under the rug for this purpose.) 7. Object-Oriented Analysis and Design Using Python and UML The aim of this book is to teach analysis, design, and patterns as if they were as important as language syntax or basic data structures. The book would be aimed at sophomores who have learned an object-oriented language (not necessarily Python) in a first-year course. It would introduce both the idea of design patterns, and the basic elements of the Unified Modeling Language (UML), and then show how to apply both to a variety of web-enabled applications. The emphasis of the book would be how to analyze a problem methodically, and how to design a program, or set of programs, to meet users' needs. Liberty's "Beginning Object-Oriented Analysis and Design", and Rosenberg and Scott's "Use-Case Driven Object Modeling with UML", would both be good inspirations, but in order to really be successful, this book would have to include many more examples, sample questions, and back-of-the-book answers than either. 8. Software Tools for Scientists and Engineers I have a confession to make. I sat down to start writing this book four years ago, and found that I couldn't, because existing software engineering tools were so hard to learn. I found out the hard way that most scientists and engineers have better things to do with their time (like science and engineering) than learning how to write non-trivial makefiles, or re-installing Gnats. They're not stupid --- many of them really are rocket scientists --- but they can tell the difference between intrinsic and accidental complexity, and don't have a lot of respect for how much of the latter there is in modern computing. The aim of the Software Carpentry project (www.software-carpentry.com) is to create tools that are worth describing. If it succeeds, I hope that someone will take those tools, and Python itself, and use them to show computational scientist and engineers how to capture software requirements, write up designs, create test plans, accommodate special features of different platforms, and everything else that makes up the "other 90%" of programming. ---------------- Greg Wilson is an independent software developer and author. He is currently managing the Software Carpentry project on behalf of Los Alamos National Laboratory and CodeSourcery, LLC. You can find out more about the project at http://www.software-carpentry.com, or reach Greg at gvwilson(a)nevex.com. Sent via Deja.com http://www.deja.com/ Before you buy.

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fetch a html page via proxy?
by bayernmREMOVEME＠hotmail.com Feb. 4, 2000

Feb. 4, 2000

I need to fetch a page from the web but the linux machine doesn't have direct connection to the net. It needs to go thru a proxy to connect to the web. How can I do this with Python? I know how to write Python code that fetch the page directly, but I can't find any information about the proxy part. thanks in advance. Ricardo Jamin bayernm<@t>hotmail.com www.jps.net/klinsi/main/

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Stackless 1.01 Homepage
by Christian Tismer Feb. 4, 2000

Feb. 4, 2000

"Why should I care about this, isn't my Python fine"? If you know what Generators, Coroutines and Continuations are about and want to have them at your fingertips, this is the real thing for you. If not, how about speed? About 5 percent faster, binary compatible as a drop-in replacement for your python15.dll, unlimited recursion, why not give it a try? Just click on the installer :-) Stackless Python 1.01 with Continuations 0.6 can now be downloaded from a web page: http://www.tismer.com/research/stackless/ Fact sheet, links to documentation, source and binaries can be found there. Source and binary distribution have been split. The Windows binaries come with a Wise installer. SLP has been successfully compiled on Solaris (Thanks to Jeff Collins). It will be used on PalmIII, to solve the 4k stack problem. Version 1.01 is a small clean-up for non-Windows platforms. <P><A HREF="http://www.tismer.com/research/stackless/">Stackless Python 1.01 + Continuations 0.6</A> - a version of Python 1.5.2 that does not need space on the C stack, and first-class callable continuation objects for Python. (20-Jan-2000) Christian Tismer Mission Impossible 5oftware Team

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ODBC and mxODBC
by Timothy Grant Feb. 4, 2000

Feb. 4, 2000

Hi, Has anyone got any tips on configuring mxODBC, or ODBC in general on a Linux box? I have a Linux box running PostgreSQL with the ODBC system installed. I can access it just fine from a Windows machine running mxODBC, but I have yet to be able to figure out how to get it to work from my own development machine which is a Linux notebook running RH6.1 I can access the database just fine using the PyGreSQL module, but I really want to use mxODBC so that I can do cross platform development. This is probably more of a ODBC question than a Python question, but any help would be appreciated. -- Stand Fast, tjg. Chief Technology Officer tjg(a)exceptionalminds.com Red Hat Certified Engineer www.exceptionalminds.com Avalon Technology Group, Inc. (503) 246-3630 >>>>>>>>>>>>EXCEPTIONAL MINDS, INNOVATIVE PRODUCTS<<<<<<<<<<<<

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glob in tcl/tk drops first char
by Sverker Nilsson Feb. 4, 2000

Feb. 4, 2000

Hi, I just started to try out Python end of last year. Seems really cool! I have quite a few libraries installed now and it works great but I run into a problem a few days ago that seems to have something to do with Tk. I traced it down to the glob function in Tk/Tcl. It seems to drop every first character in every filename. It showed up from using tkfbox (called from tkFileDialog I think) but glob behaved the same when called directly from wish.py. The native wish8.0 works all right. Anybody has any idea? Thanks! This shows how the error appears - glob drops every first char! nicosys [19] ls wish* wish.py* wish.pyc nicosys [20] python wish.py % glob wish* TclError: no files matched glob pattern "wish*" % glob *.py ttrDialog.py anPage.py imeViewer.py hellWindow.py rownian.py anvasevents.py ialog.py lectrons.py anoi.py ello.py magedraw.py mageview.py ill.py isttree.py box.py ewmenubardemo.py ptionmenu.py aint.py edemo.py egexdemo.py mt.py olitaire.py ortvisu.py vkill.py witch.py kman.py ish.py % glob ish* ish.py ish.pyc % nicosys [21] This is some of my configuration: nicosys [23] python Python 1.5.2 (#25, Jan 31 2000, 00:36:50) [GCC 2.7.2.1] on linux2 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam >>> nicosys [1] uname -a Linux nicosys 2.0.29 #4 Thu Jan 27 01:47:58 MET 2000 i586 unknown nicosys [2] ldd /usr/local/bin/python libreadline.so.2 => /usr/lib/libreadline.so.2.0.0 libtermcap.so.2 => /lib/libtermcap.so.2.0.8 libtk8.0.so => /usr/lib/libtk8.0.so libtcl8.0.so => /usr/lib/libtcl8.0.so libX11.so.6 => /usr/X11/lib/libX11.so.6.1 libdl.so.1 => /lib/libdl.so.1.8.5 libm.so.5 => /lib/libm.so.5.0.9 libc.so.5 => /lib/libc.so.5.4.46 nicosys [3] ldd /usr/lib/libtk8.0.so /usr/lib/libtk8.0.so => /usr/lib/libtk8.0.so libc.so.5 => /lib/libc.so.5.4.46 nicosys [5] ldd /usr/lib/libtcl8.0.so /usr/lib/libtcl8.0.so => /usr/lib/libtcl8.0.so libc.so.5 => /lib/libc.so.5.4.46 nicosys [7] ldd /lib/libc.so.5.4.46 /lib/libc.so.5.4.46 => /lib/libc.so.5.4.46 nicosys [8] gcc -v Reading specs from /usr/lib/gcc-lib/i486-linux/2.7.2.1/specs gcc version 2.7.2.1 nicosys [9] Regards, Sverker Nilsson

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Compile Problem Imaging-1.0/Tk
by Tilo Schwarz Feb. 3, 2000

Feb. 3, 2000

Hi all, (our newsserver was down some days and it seems to me that my first posting didn't do through to comp.lang.python ... so I try it again.) I successfully compiled the libImaging subdir of Imaging-1.0, but I have a problem compiling the Tk subdir (I'm no tk expert). I followed the install instructions, but I get the error: > make [snip] gcc -fpic -IlibImaging -I/usr/local/include -I/usr/local/include -DWITH_TKINTER -I/usr/X11R6/include -I/usr/local/include -O2 -m486 -fno-strength-reduce -I/usr/include/python1.5 -I/usr/include/python1.5 -DHAVE_CONFIG_H -c ./Tk/tkImaging.c ./Tk/tkImaging.c: In function `PyImagingPhoto': ./Tk/tkImaging.c:76: warning: passing arg 1 of `Tk_FindPhoto' from incompatible pointer type ./Tk/tkImaging.c:76: too many arguments to function `Tk_FindPhoto' make: *** [tkImaging.o] Error 1 I couldn't find something about that in an FAQ. I have only one tk.h on my system (SUSE 6.2), which is in /usr/X11R6/include/tk.h and the libs seem to be alright: /usr/X11R6/lib/libtk8.0.a /usr/X11R6/lib/libtk8.0.so /usr/lib/libtcl8.0.a /usr/lib/libtcl8.0.so Now I have in Tk/tkImaging.c:76: photo = Tk_FindPhoto(interp, argv[1]); and in tk.h: EXTERN Tk_PhotoHandle Tk_FindPhoto _ANSI_ARGS_((char *imageName)); which obviously doesn't match. Now in tk8.0.h I found a "good" match: EXTERN Tk_PhotoHandle Tk_FindPhoto _ANSI_ARGS_((Tcl_Interp *interp, char *imageName)); but if I include tk8.0.h, I get: gcc -fpic -IlibImaging -I/usr/local/include -I/usr/local/include -DWITH_TKINTER -I/usr/X11R6/include -I/usr/local/include -O2 -m486 -fno-strength-reduce -I/usr/include/python1.5 -I/usr/include/python1.5 -DHAVE_CONFIG_H -c ./Tk/tkImaging.c In file included from ./Tk/tkImaging.c:42: /usr/X11R6/include/tk8.0.h:1275: parse error before `Tcl_Obj' /usr/X11R6/include/tk8.0.h:1468: parse error before `Tcl_Obj' /usr/X11R6/include/tk8.0.h:1495: parse error before `Tcl_Obj' /usr/X11R6/include/tk8.0.h:1542: parse error before `Tcl_Obj' /usr/X11R6/include/tk8.0.h:1551: parse error before `Tcl_Obj' make: *** [tkImaging.o] Error 1 Any ideas? Thanks for any help! Bye Tilo -------------------- Tilo Schwarz, DaimlerChrysler, Research Center Ulm, FT3/AB Address: Wilhelm-Runge-Str.11, P.O. Box 23 60, 89013 Ulm, Germany Phone: +49 731 505 2376 Email: tilo.schwarz(a)daimlerchrysler.com

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Why Perl do But Python can't?
by �ܹ� Feb. 3, 2000

Feb. 3, 2000

I write a CGI useing Perl to modify passwd,set the CGI mod to 4755,and it really do. But When I change it into Python with the same function,set mod to 4755,but it not use the Setuid bit. Someone know the difference of Perl and Python in the CGI running mode? Luckey(a)soim.net 2000.1.30

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anydbm - a simple question
by Randall Hopper Feb. 3, 2000

Feb. 3, 2000

Straight from the Effbot guide, but it fails when you try to add an element. Any idea what it doesn't like? >>> import anydbm >>> db = anydbm.open( "database", "c" ) >>> db[ "1" ] = "one" Traceback (innermost last): File "<stdin>", line 1, in ? File "/home/rhh/software/python-1.5.2/lib/python1.5/dumbdbm.py", line 111,\ in __setitem__ (pos, siz) = self._addval(val) File "/home/rhh/software/python-1.5.2/lib/python1.5/dumbdbm.py", line 87, \ in _addval f.write('\0'*(npos-pos)) TypeError: can't multiply sequence with non-int -- Randall Hopper aa8vb(a)yahoo.com

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shelve implementation
by Robin Becker Feb. 3, 2000

Feb. 3, 2000

can someone explain why shelve uses StringIO as an intermediate rather than doing the pickles direct ie shelve uses def __getitem__(self, key): f = StringIO(self.dict[key]) return Unpickler(f).load() def __setitem__(self, key, value): f = StringIO() p = Pickler(f) p.dump(value) self.dict[key] = f.getvalue() whereas I would have done def __getitem__(self, key): return loads(self.dict[key]) def __setitem__(self, key, value): self.dict[key] = dumps(value) -- Robin Becker

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Charts
by Thierry Thelliez Feb. 2, 2000

Feb. 2, 2000

Is there any packages for creating charts (histograms, scattered plots, line charts,...) in Python ? Thanks Thierry

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