🌐 Mailman 3 December 2009 - Python-list - python.org

NumPy installation won't import correctly
by Ethos Dec. 2, 2009

Dec. 2, 2009

I installed NumPy for python 2.6 on my leopard macbook, using the nifty mac installer they now provide. I have the 2.6 official python distro installed on my computer, in addition to the 2.5 that is native on the mac. When I went to test out the installation, with 2.6, it gave me this: >>> import numpy Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/Library/Frameworks/Python.framework/Versions/2.6/lib/ python2.6/site-packages/numpy/__init__.py", line 132, in <module> import add_newdocs File "/Library/Frameworks/Python.framework/Versions/2.6/lib/ python2.6/site-packages/numpy/add_newdocs.py", line 9, in <module> from lib import add_newdoc File "/Library/Frameworks/Python.framework/Versions/2.6/lib/ python2.6/site-packages/numpy/lib/__init__.py", line 4, in <module> from type_check import * File "/Library/Frameworks/Python.framework/Versions/2.6/lib/ python2.6/site-packages/numpy/lib/type_check.py", line 8, in <module> import numpy.core.numeric as _nx File "/Library/Frameworks/Python.framework/Versions/2.6/lib/ python2.6/site-packages/numpy/core/__init__.py", line 5, in <module> import multiarray ImportError: dlopen(/Library/Frameworks/Python.framework/Versions/2.6/ lib/python2.6/site-packages/numpy/core/multiarray.so, 2): no suitable image found. Did find: /Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site- packages/numpy/core/multiarray.so: unknown required load command 0x80000022 The file that it claims it can't find a suitable image for does in fact exist in that directory. I'm stumped. Funny thing is, when I imported it using python2.5, it worked just fine. numpy.test(1,10) ran without a hitch. Thanks for the help. Please redirect me if this question belongs elsewhere.

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Re: xmlrpc idea for getting around the GIL
by "Martin v. Löwis" Dec. 2, 2009

Dec. 2, 2009

> What I meant was that I am *not allowed* to make calls to the CPython > API from the threads I currently have because these threads are high > priority and are never allowed to make blocking calls. Fortunately, > each of these threads can have a completely separate interpreter, so > my idea was to create a daemon process for each thread. This daemon > would contain the libpython symbols and would make the CPython calls. > This would keep my current threads from having to contend over the > single GIL. If this ("never allowed to make blocking calls") is a strict requirement, then this is no solution, either. Communicating to the remote process would involve IO, and all IO operations may block. Of course, you might use non-blocking IO, in which case I wonder how the thread continues if it finds that the IO is blocking. I also wonder how the thread will find out that the result of the computation is available, when it is not allowed to wait for the result. In any case, I don't think you'll need a multi-process solution; a single-process multi-threading approach will do fine. Just create *another* thread, that runs at a low priority and is allowed to block. Run the Python interpreter in that thread (create multiple of these if you need them). Then, use some queuing producer-consumer communication between the high-priority thread and the low priority thread. Have the high priority threads put requests into the queue, and the low priority thread take them from the queue, dispatching them to Python. Make sure you use non-blocking synchronization on the queue, or else priority inheritance if you can get permission to do so. > Damn you, Gil. It may sound to you like the GIL is responsible for that. However, consider a world where the GIL was removed in Python. There would *still* be synchronization for data structures be going on. As you are not allowed to have any blocking operation in the high-priority threads, you *still* couldn't directly call the Python interpreter (or any other thread-safe library) from your high-priority threads. Regards, Martin

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Re: DOM related question and problem
by bla bla Dec. 2, 2009

Dec. 2, 2009

Nice post on extracting data, simple and too the point :), I use python for simple html extracting data, but for larger projects like the web, files, or documents i tried <a href="http:// www.extractingdata.com">extract data</a> which worked great, they build quick custom screen scrapers, extracting data, and data parsing programs

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teaching python using turtle module
by Brian Blais Dec. 2, 2009

Dec. 2, 2009

Hello, I was just playing with the turtle module, and thought it was an interesting way to augment the introduction to python (I teach college students, who haven't had any programming). It's a great way to introduce functions, for-loops, and general program structures. After a bit of playing, I realized that I couldn't think of many examples which use turtle with conditional structures (if- and while- statements), or functions that return values, as opposed to "procedures" like: def square(length): forward(length) right(90) forward(length) right(90) forward(length) right(90) forward(length) right(90) If-statements could possibly be used with some sort of random behavior (if rand()<0.5 ...). Are there any other situations, using turtle, that these structures would be natural? thanks, Brian Blais -- Brian Blais bblais(a)bryant.edu http://web.bryant.edu/~bblais

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How to set object parameters nicely?
by allen.fowler Dec. 1, 2009

Dec. 1, 2009

Hello, I've got a bunch of code that looks something like: class MyOb(object): def __init__(self, p1=None, p2=None, p3=None, ...): self.p1 = p1 self.p2 = p2 self.p3 = p3 self.pN = ... ob1 = MyOb(p1="Tom", p3="New York") ob2 = MyOb(p1="Joe", p2="joe@host", p3="New Jersey") ... and so on. This is fine for only a few parameters, but it's very ugly and a lot of duplicate typing once I've got 10+ parameters and 5 kinds of objects. Is there a better way to do this? Thanks, :)

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Report spammers to their service provider for great justice (was: can you say it please)
by Ben Finney Dec. 1, 2009

Dec. 1, 2009

Steven D'Aprano <steve(a)REMOVE-THIS-cybersource.com.au> writes: > On Tue, 01 Dec 2009 00:31:51 -0800, Processor-Dev1l wrote: > > > does it mean ... > > Please don't respond to religious nutters or spammers, you only > encourage them. Instead, report them to the provider they used to send their message, as an abuse of service. Look in the message header; in the overwhelming majority of cases they will have used Google, so you'll find a ‘Complaints-To’ field with an email address as its value. Forward the entire message to that address and explain the message is an abuse of service. Yes, this actually does reach real people who can do something about it (though you won't get a response); it's the reason we don't see *even more* of this crap. -- \ “I was sleeping the other night, alone, thanks to the | `\ exterminator.” —Emo Philips | _o__) | Ben Finney

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Re: Creating a local variable scope.
by markolopa Dec. 1, 2009

Dec. 1, 2009

Hi Dave, Since you feel like discussing my weird idea of Python reform :-) lets go... On 30 Nov, 11:29, Dave Angel <da...(a)ieee.org> wrote: > Somehow you seem to think there's some syntax for "creating" avariable. In fact, what's happening is you're binding/rebinding a name > to an object. And if you forbid doing this inside the loop, for names > that exist outside the loop, then most of the useful work the loop does > becomes impossible. Remember, in Python, there's no declaration of avariable(except the global statement, which does it sort-of). You are right, I have not used precise terms. Let's use examples then. > So you'd > be disallowing the following: > > counter = 5 > for item in itemlist: > if item > 19: > counter = counter + 5 In this example, I would allow the expected behaviour. Since "counter" was bound in the outer loop, the new binding got in the inner loop would persist after the end of the "if" and the "for" block. Other examples: if True: a = 5 print a would produce an error while a = 3 if True: a = 5 print a would print 5 (and not 3). But now I realise that one of my bugs wouldn't be solved, so I believe you have managed to convince me that my idea does not make much sense...:-) > The only way I can think you possibly want this is if you're just > referring to "loop variables", such as "item" in the above example. The > problem is that on many loops, for example a "while" loop, there's no > such thing. This would already be great. I believe that most bugs I've had related to this issue are due to accidental reuse of loop variables. But treating the loop variables as a special case is perhaps not very elegant. Greetings, Marko

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Python reflection and loading/calling external module classes
by cmckenzie Dec. 1, 2009

Dec. 1, 2009

Hi! I've been putting off playing with Python for sometime now and I recently came up with a worthwhile project for my first hack. One technical challenge I'm trying to work out is dynamically loading modules from a directory (glob'd for a specific filename format) then importing them for calling later. Basically my modules follow this structure: class sample():

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Re: Can't print Chinese to HTTP
by "Martin v. Löwis" Dec. 1, 2009

Dec. 1, 2009

Gnarlodious wrote: > Hello. The "upgrade to Python 3.1 has been disaster so far. I can't > figure out how to print Chinese to a browser. If my script is: > > #!/usr/bin/python > print("Content-type:text/html\n\n") > print('晉') > > the Chinese string simply does not print. It works in interactive > Terminal no problem, and also works in Python 2.6 (which my server is > still running) in 4 different browsers. What am I doing wrong? BTW > searched Google for 2 days no solution, if this doesn't get solved > soon I will have to roll back to 2.6. > > Thanks for any clue. In the CGI case, Python cannot figure out what encoding to use for output, so it raises an exception. This exception should show up in the error log of your web server, please check. One way of working around this problem is to encode the output explicitly: #!/usr/bin/python print("Content-type:text/plain;charset=utf-8\n\n") sys.stdout.buffer.write('晉\n'.encode("utf-8")) FWIW, the Content-type in your example is wrong in two ways: what you produce is not HTML, and the charset parameter is missing. Regards, Martin

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Re: problem with lambda / closures
by Jussi Piitulainen Dec. 1, 2009

Dec. 1, 2009

Terry Reedy writes: > definitions. Lambda expressions create functions just like def > statements and are not closures and do not create closure unless > nested within another function definition. Thinking otherwise is Seems quite closed in the top level environment to me: Python 2.3.4 (#1, Jul 16 2009, 07:03:37) >>> k = 'outer' >>> f = lambda : k >>> def test(): ... k = 'inner' ... return f() ... >>> test() 'outer' >>> k = 'thing' >>> test() 'thing'

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