[Tutor] multiprocessing: Correct usage of pool & queue?
Hello, I have a list of tasks/items that I want handed off to threads/processes to complete. (I would like to stick with process if I could, since there is some CPU work here. ) Each task involves some calculations and a call to a remote server over urllib2/HTTP. The time to complete each task varies from 1 to 20 seconds depending on a number of factors including variable delay on the remote server. I would like to: 1) Have a maximum of 20 "in-flight" tasks. (thus worker processes?) 2) Not overload the external server that each task is calling. No more than "3 new tasks" per second. More "waiting" tasks may be OK, i need to test it. 3) Certain tasks in my list must be processed in the correct order. (I guess the asignment logic must somehow tag those to by done by the same worker?) Do any of you have suggestions? Can someone point me in the direction of sample code for this? Thank you, :) ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] string.title(): correct?
Hello, "He's a great guy".title() Gives me: "He'S A Great Guy" I expected: "He's A Great Guy" Did i miss something here? Thank you, :) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Fixing "nearly ASCII" data file?
Hello, I have some CSV data from Office / OpenOffice in "nearly ASCII" format. This is just basic text but it it stored as UTF-8, and has curly quotes, etc. Is there a way to easily read the file as ASCII by forcing these to the standard ASCII equivalents? Thank you ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Configuaration files and paths?
> >
> > FWIW:
> >
> > When using relative paths I got extra ../../ terms, so I changed
> join_relative() to:
> >
> > def join_relative(base, path):
> > return os.path.normpath(os.path.join(script_dir(base), path))
> >
> >
> > Seems to work...
>
>
> Yeah, good catch ... looks great, and thanks for sharing your mod.
>
Glad I could return the favor. :)
Since then, I took it a bit further for use in my code... I am not finished
with it yet, but am curios what you think. (I am not sure named things right
or structured it logically)
###
import os
class HomePath(object):
"""For finding paths based on a home/install directory.
"""
def __init__(self, home_dir = None, home_file = None):
"""Must be called with either a path to a directory or, as a
shortcut, a file in that directory.
"""
if home_file != None:
# Set home based on a path to a file in its directory
self.home = os.path.normpath(self.fix_path(home_file))
elif home_dir != None:
# Set home based on its path
self.home = os.path.normpath(self.get_dir(home_dir))
else:
raise Exception("Must call with either a path to a directory
or, as a shortcut, a file in that directory.")
def abs(self, rel_from_home):
"""Return an absolute path when passed a path relative to home.
"""
return self.join_relative(self.home, rel_from_home)
def fix_path(self, base):
return os.path.realpath(os.path.abspath(base))
def get_dir(self, base):
return os.path.dirname(self.fix_path(base))
def join_relative(self, base, path):
return os.path.normpath(self.fix_path(os.path.join(self.home,
path)))
#
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Re: [Tutor] Configuaration files and paths?
> > Something like this ... > > # lib/mypaths.py > # -- > > import os > > def script_path(base): > return os.path.realpath(os.path.abspath(base)) > > def script_dir(base): > return os.path.dirname(script_path(base)) > > def join_relative(base, path): > return os.path.join(script_dir(base), path) > > # app.py > # -- > > ... > > from lib.mypaths import join_relative > print join_relative(__file__, 'config/prefs.ini') > > # this may work when calling from > # other modules, I suppose (untested) > > import sys > print join_relative(sys.argv[0], 'config/prefs.ini') > > ... FWIW: When using relative paths I got extra ../../ terms, so I changed join_relative() to: def join_relative(base, path): return os.path.normpath(os.path.join(script_dir(base), path)) Seems to work... ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Configuaration files and paths?
> Martin Walsh > > Allen Fowler wrote: > > > > > > > As a follow-up question, how do give my modules stored under ./lib access > > to > the data in my ConfigParser object? (For instance, database connection > string, > storage path, etc.) > > > > I guess a global ConfigParser object would work, but that seems wrong. > > > > And yet, to me it seems wrong to have more than one instance of config > data floating around. Instead of using a global you can pass the config > object, or just the appropriate attributes, around to your lib > functions/classes, as necessary -- and keep the flow in your main > script. For example (highly speculative, FWIW), > > # app.py > from database.connection import getcursor > from lib.persist import Storage > > def main(): > confp = ConfigParser() > confp.read(join_relative(__file__, 'config/prefs.ini')) > config = confp.defaults() > > curs = getcursor(config[db_connection_string]) > > ... > > storage = Storage(config[storage_path]) > > I hear your point. It makes sense. The above sample code seems like the way to go... if I can structure my modules like that. For an object that needs many settings, what about passing in an instance of ConfigParser? (Or should I extract the settings to a dict, first?) Thank you again, :) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Configuaration files and paths?
> > Assuming the application could be invoked in odd ways that may alter the > notion of the current working directory, how do I unambiguously find the > absolute path to the current python source file? (So I can load the nearby > .ini) > > I use a helper function that calculates the absolute path of my app > script, then I am able to os.path.join relative elements to my heart's > content. I haven't had a problem with this approach so far, which of > course doesn't mean it's the right way, or even a correct implementation > for that matter. > > Something like this ... > > # lib/mypaths.py > # -- > > import os > > def script_path(base): > return os.path.realpath(os.path.abspath(base)) > > def script_dir(base): > return os.path.dirname(script_path(base)) > > def join_relative(base, path): > return os.path.join(script_dir(base), path) > > # app.py > # -- > > ... > > from lib.mypaths import join_relative > print join_relative(__file__, 'config/prefs.ini') > > # this may work when calling from > # other modules, I suppose (untested) > > import sys > print join_relative(sys.argv[0], 'config/prefs.ini') > That is really great. Thank you. I wonder why something like this is not in the standard library. Seems like an often needed function. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Configuaration files and paths?
> > What is the recommended way to configure my application find the various > database and/or configuration files it needs? > > Recommemded by whom? A lot depends on the OS. Apple for example have one set > of > recommendations for MacOS, Windows has another and Linux has several to > choose > from! > Thank you good point. Planning on using a ConfigParser based .ini file located in the ./config folder. > > For instance my folder layout: > > > > /path_to_app/app.py > > /path_to_app/lib/ > > /path_to_app/database/ > > /path_to_app/config/ > > /path_to_app/photos > > > > and so on. I would like to make an .ini in the config folder > > Seems fair enough, however on a Unix system you should also consider allowing > the user to have their own personalised version in their home directory. Thus > at > startup you get the current user ID / home directory and look for a suitable > config file. If it exists read it, if not read the default one in your config > directory. > > > 1) How does my main app file find the config file in the first place? > > Generally use a relative path so normally your app will run from its home > folder > so you can look in ./config. You might also set a system environment variable > - > for example the CLASSPATH or PYTHONPATH variables, or the ORACLE_HOME used by > Oracle for their database. If the environment var is not set then look in > ./config > Assuming the application could be invoked in odd ways that may alter the notion of the current working directory, how do I unambiguously find the absolute path to the current python source file? (So I can load the nearby .ini) As a follow-up question, how do give my modules stored under ./lib access to the data in my ConfigParser object? (For instance, database connection string, storage path, etc.) I guess a global ConfigParser object would work, but that seems wrong. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Configuaration files and paths?
Hello, What is the recommended way to configure my application find the various database and/or configuration files it needs? For instance my folder layout: /path_to_app/app.py /path_to_app/lib/ /path_to_app/database/ /path_to_app/config/ /path_to_app/photos and so on. (app.py being the main file, and the lib folder containing my custom modules.) I would like to make an .ini in the config folder that contains entries that point to the other folders. Seems like a resonable idea. So my questions are: 1) How does my main app file find the config file in the first place? 2) How should I point to those other folders in the ini file? Thank you ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Suggested source code folder layout
> > My 2 cents... > > 1) Since you are describing your source code layout, any virtual > environment should be outside. A virtual environment (virtualenv) is > part of deployment and not part of source. If you need to make a > reproducible deployment environment, then you need a deployment system > such as zc.buildout. You would store just the recipe for the > environment in source, but not the resulting buildout. Your build > recipe will typically go in the top of your source tree. > > http://pypi.python.org/pypi/zc.buildout/ > Good point about keeping the virtualenv out of the source tree in favor of "recipe", and copying the modules to lib or site-packages upon deployment. zc.buildout seems like a powerful tool, but I'm not at all clear on how to use it for this sort of task. (All the tutorials I can find to seem to zope related.) Do you have any examples you can share? ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Suggested source code folder layout
Hello, I'm looking for some suggestions as to the filesystem source code layout for a new project. Here is what I am thinking so far: root_folder/ - app/ -- Code for our pylons/django/TG/etc web app - web/ -- Public static web files (and wsgi / fastCGI connector files) - db/ -- SQlite DB - scripts/ -- Various custom programs that will also interact with the DB / app. (Some cron, some interactive.) However, I am still wondering about a couple of items: 1) Where to create the virtualpython installation that will be used by both the app and the scripts. 2) Where to put our in-house created python modules that will be imported by both the app and scripts. Thank you, :) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Spell checking source code?
Hello, Are there any utilities to help "spell check" source code? (Docstrings, etc) Thank you, :) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Sample python file/module templates?
Hello, In terms of in-code documentation of function / section headers, change logs, etc. Are there well-done sample files I can use as inspiration? Thank you, :) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Mapping to an equivalent / similar object?
> The difference between objects is measeured by their interfaces not their
> data
> so provided the supplier objects all use the same operations of a Flavor then
> its not too bad. You can either create subclasses of Flavor for each
> manufacturer that retuirns the requisite list of attributes (but requires
> ongoing changes for every new manufacturer - eek!) or you can write a method
> of
> Flavor that takes a list (or dictionary?) of required attributes and returns
> the
> values. It can also raise exceptions if asked for unsupported attributes, or
> return None, in which case the Supplier object provides a suitable default.
>
Hmm. I'll have to read that a couple of times.
> This way you can limit the changes for a new supplier. You might also be able
> to
> data drive the Supplier object to make the required list of attributes
> configurable(via a database or file?). Then you only need subclasses of
> Supplier
> for the actual interface types (EDI, v FTP, v http v email etc).
>
> > How should the mapping between the CanonicalFlavor('Vanilla') object and
> ManufAFlavor('Vanilla') / ManufBFlavor('Vanilla') objects be handled.
>
> If the mapping is one to many I don;t think you need to maintain it - at
> least
> not in the objects. Just pass the Flavor object to the supplier object. Let
> the
> supplier query the Flavor for the data it needs.
>
> If the choice of supplier was driven by Flavor characteristics then the
> selection method would be in the Flavour and then you'd need to keep a list
> of
> suppliers in the Flavor. But since
> the supplier is chosen from external factors the Flavor doesn't need to know
> about its supplier. And the supplier only needs to know about how to query a
> flavour.
>
What about just Flavor() objects and a customised "per-manufacture" SupplierA()
/ SupplierB() objects that internally knows how to generate an order from a
passed in Flavor() object? (Which would also raise a CantMakeFlavor error if
this manufature can't supply the required flavor.)
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[Tutor] Mapping to an equivalent / similar object?
Hello,
Imagine the relationship between an Ice Cream retail store and the several
manufactures that supply it's flavors.
The retail store has a single list of flavors and any given flavor can be made
by one or more manufactures. (Most are made by several.)
The store's stock monitoring system will generate a list of Flavor() objects
that need to be ordered. Say: Flavor('Vanilla'), or better yet,
CanonicalFlavor('Vanilla')
The store's ordering system takes as input a CanonicalFlavor('Vanilla') object
that needs to be purchased, and must route this to a manufacturer's ordering
system. The choice of which manufacture to use is based on external factors.
However, each manufacturer's ordering system is different, and each expects a
radically different variation of a Flavor object. (Different ingredients,
parameters, etc. )
How should the mapping between the CanonicalFlavor('Vanilla') object and
ManufAFlavor('Vanilla') / ManufBFlavor('Vanilla') objects be handled.
(Or is this the wrong way to do this?)
Thank you,
:)
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Re: [Tutor] Shared FIFO?
> "Allen Fowler" wrote > > I have several CGI scripts that I would like coordinate via a "First In / > First Out" style buffer.That is, some processes are adding work units, > and > some take the oldest and start work on them. > > > > What is the right way to do this?I suppose I could use an SQL server or > SQlite , but that seems very complex for just a FIFO. > > Given how easy it is to use something like SqlLite from Python I don't think > its > an unreasonable approach and it avoids or eases some of the hidden > complexities > around using simple files (such as locking issues). > Yeah. Now that I think about there are ton of small issues that using sqlite would take care of. For clarification, this is not just for CGI scripts... there will be cron initiated processes and perhaps a TurboGears app accessing the same buffer. Since this sounds like it's been done before, can anyone direct me to tutorial or how-to on the subject? thank you, :) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Shared FIFO?
Hello, I have several CGI scripts that I would like coordinate via a "First In / First Out" style buffer.That is, some processes are adding work units, and some take the oldest and start work on them. What is the right way to do this?I suppose I could use an SQL server or SQlite , but that seems very complex for just a FIFO. Thank you, :) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Calling super classs __init__?
> Nowadays the best practice for invoking a method from all superclasses > (yes, multiple inheritance) is this: > > class SubClass(BaseClass): > def __init__(self, t, *args, **kw): > super(SubClass, self).__init__(*args, **kw) > # do something with t > > That way you let Python decide which superclasses your SubClass has, > instead of hard-coding it in several places. > Excellent. Thank you. This seems far more logical. Is there a proper way to handle the case when SubClass() is called using positional arguments, and you do not desire "t" to be at the beginning? Thanks again, :) Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Calling super classs __init__?
> > What's the most "pythonic" way to make this work? > > class BaseClass(object): > def __init__(self, x, y, z, foo='foo'): # whatever > # etc > > class SubClass(BaseClass): > def __init__(self, t, *args, **kw): > BaseClass.__init__(self, *args, **kw) > # do something with t > > This does mean that the special sub class argument has to come before > the base class arguments when you create instances. > > Whether you call BaseCla Thank you... Excellent idea. I haven't tried it yet, but I suppose **kwarg.pop()'ing and *args manipulation could help ease subclass instantiation call signature limitations. (?) Thanks, :) Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Calling super classs __init__?
> > class MySubClass(MySuperClass): > > > > def __init__(self, just_a_sub_option): # what about other args? **args? > > I think I would go ahead and list the superclass parameters and put the > new one at the end: > def __init__(self, opt_1, opt_2, opt_3, opt_n, just_a_sub_option): > > > MySuperClass.__init__()# Should this be first? > What args to use? **args? > > MySuperClass.__init__(self, opt_1, opt_2, opt_3, opt_n) > > John's method will also work but I prefer to add the new parameter at > the end of the argument list. (Hmm.. I should have pointed out that I generally use keyword args. ) Right. So, I can certainly call the MySuperClass.__init__() with a long list of kwargs, but that gets annoying quickly when the superclass is also under active development and it's call signature frequently changes. Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] kwargs to object proporties?
Hello, What's the best way convert keyword arguments to object properties? Basically, I have a defined list of valid object properties that I'd like to optionally specify in the call to the constructor. I've got ideas about using __getattr__ but I'm not sure if that's the right way. Plus, that kind of makes it hard to use tab completion of objects in iPython. Thanks, :) Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Calling super classs __init__?
Hello, Now, perhaps this not the best way write code, but I have a few questions regrading calling the super classes constructor: I have a super class that accepts many arguments to it's constructor, and a subclass that should define one additional argument. What's the most "pythonic" way to make this work? class MySuperClass(object): def __init__(self, opt_1, opt_2, opt_3, opt_n): # stuff done here pass class MySubClass(MySuperClass): def __init__(self, just_a_sub_option): # what about other args? **args? # do stuff with "just_a_sub_option" MySuperClass.__init__()# Should this be first? What args to use? **args? pass Basically, I'd like to avoid maintaining a verbose list of arguments in the subclass. Thanks, :) Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Simple reg-ex syntax?
findall is great. Thank you. :)
- Original Message
> From: Chris Fuller <[EMAIL PROTECTED]>
> To: tutor@python.org
> Sent: Thursday, March 13, 2008 5:10:43 AM
> Subject: Re: [Tutor] Simple reg-ex syntax?
>
>
> How I would improve this:
>
> compile the regular expression. This is more efficient.
> self.digit_extractor = re.compile('(\d+)')
>
> then, use the findall method:
> self.allNumbers = self.digit_extractor.findall(self.aString)
> which will even work with multiline strings, but doesn't convert to integers.
>
> To convert, use a list comprehension:
> self.allNumbers = [int(i) for i in self.digit_extractor.findall(self.aString)]
>
> Cheers
>
> On Wednesday 12 March 2008 21:59, Allen Fowler wrote:
> > Hello,
> >
> > I have code that looks something like:
> >
> > self.aString = "abc123xyz"
> > self.theNumber = int(re.search('(\d+)',self.aString).group())
> >
> > Is there a more Pythonic way of doing this? (Both the reg-ex and the Int
> > coercion.) How about when I will need to extract more than one substring?
> >
> > Thank you,
> >
> > :)
> >
> >
> > ___
> >_ Never miss a thing. Make Yahoo your home page.
> > http://www.yahoo.com/r/hs
> >
> > ___
> > Tutor maillist - Tutor@python.org
> > http://mail.python.org/mailman/listinfo/tutor
> ___
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>
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Re: [Tutor] Correct way to call an outside program?
Thank you for the help. :)
- Original Message
simplest way to run external commands !
import os
cmd="/usr/bin/ssh 10.0.0.20 uptime"
os.popen(cmd)
my cmd is just an example, use any cmd you want & its output will be displayed
to you.
hope this helps
[SNIP]
subprocess.Popen().communicate() will do it:
In [1]: import subprocess
In [7]: x=subprocess.Popen('ls', stdout=subprocess.PIPE,
stderr=subprocess.PIPE).communicate()
In [10]: print x[0]
If you just want stdout and stderr of the subprocess to go to stdout and
stderr of the calling process you can omit those arguments to Popen().
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[Tutor] Correct way to call an outside program?
Hello, I need to call an external command line .exe utility from my Python script. What is the best way to capture the output (if any) and (optionally) direct it to my normal standard output? There seem to be many options... Thank you, :) Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Simple reg-ex syntax?
Hello,
I have code that looks something like:
self.aString = "abc123xyz"
self.theNumber = int(re.search('(\d+)',self.aString).group())
Is there a more Pythonic way of doing this? (Both the reg-ex and the Int
coercion.) How about when I will need to extract more than one substring?
Thank you,
:)
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Re: [Tutor] Video file metadata? (MP4/WMV)
I can't seem to find a simple description of the MP4 sepc... it might be because there is not one. :) That being said, what is the correct way to parse binary files in Python? - Original Message > From: Alan Gauld <[EMAIL PROTECTED]> > To: tutor@python.org > Sent: Tuesday, March 4, 2008 7:32:01 PM > Subject: Re: [Tutor] Video file metadata? (MP4/WMV) > > > "Allen Fowler" wrote in > > > 1) Does these exist a python module I can use to > > programatically edit the metadata in MP4 > > files? > > I don;t know of one but if you can find the spec it might > be easy enough to just edit the files using normal (binary) > file handling methods. I've certainly done that for MIDI files. > > > -- > Alan Gauld > Author of the Learn to Program web site > Temorarily at: > http://uk.geocities.com/[EMAIL PROTECTED]/ > Normally: > http://www.freenetpages.co.uk/hp/alan.gauld > > ___ > Tutor maillist - Tutor@python.org > http://mail.python.org/mailman/listinfo/tutor > Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Video file metadata? (MP4/WMV)
Hello, I have several hundred WMV video files with bad embedded author/title/date information. However, the correct information is correctly encoded in the file name.. i.e. "title-author-date.wmv" Seems like the a great job for Python. :) Also, I am about to convert these fiiles to MP4 for use on an iPod. The video software I am using will, I think, transfer the metadata from the WMV to the new MP4 files. So, two questions: 1) Does these exist a python module I can use to programatically edit the metadata in MP4 files? 2) Failing that, is there a python module I can use to edit the metadata in the WMV files? (hopeing the data makes it through the conversion..) -- Thank you Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] run in "deamon" mode?
Thank you for all the great tips... I'll try a few and see what works. I must say that I'm a bit surprised that the Python Std library does not have a module for this. Are all python scripts expected to be small user-mode utilities? Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] run in "deamon" mode?
Hello, How can a make a python script run in "deamon mode"? (on a linux box) That is, I want to run the program via "python myfile.py" and have it drop me back to the command line. The program should continue running until I kill it via it's PID, the machine shuts down, or the program itself decides to shutdown. It should _not_ die when I simply log-out, etc. Is there a standard library module to help with this? -- Thank you Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Pythonic way to "try a few times, then raise exception"?
Hello, I have a block of code buried deep in a module that I expect to fail periodically. (Calls to other machines over slow network, and such.) Generally, though, trying it a second / third will work. Is there clean way to write this on Python? Thanks __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] __getattr__(): Is this right? [w/ new code]
Umm... well. obviously I left out an __setattr__() call..
sigh.
thanks anyway...
Allen Fowler <[EMAIL PROTECTED]> wrote:
What did you try? What happened? What did you expect?
Kent
Narrowed things down a bit.
Given this class:
---
class sc(object):
def __init__(self, **kargs):
self.valid_props = [ 'foo', 'bar', 'baz' ]
for prop in self.valid_props:
if kargs.has_key(prop):
self.__setattr__(prop, kargs[prop])
def __getattr__(self,attr):
if attr in self.valid_props:
print "__getattr__ was called for %s" % attr
return 'n/a'
else:
raise AttributeError, attr
This is my in/output:
-
In [1]: some_string_a = 'foo'
In [2]: some_string_b = 'FOO'
In [3]: s = sc( foo=some_string_b )
In [4]: s.foo
Out[4]: 'FOO'
In [5]: eval('s.' + some_string_a)
Out[5]: 'FOO'
In [6]: s.__getattr__(some_string_a)
__getattr__ was called for foo
Out[6]: 'n/a'
In [7]: s.__getattr__('foo')
__getattr__ was called for foo
Out[7]: 'n/a'
In [8]: s.bar
__getattr__ was called for bar
__getattr__ was called for bar
Out[8]: 'n/a'
In [9]: s.__getattr__('bar')
__getattr__ was called for bar
Out[9]: 'n/a'
Here is what I expected:
--
Outputs 4 and 5 are fine.
Outputs 6 and 7 should have returned 'FOO'
Outputs 8 and 9 are fine. (But why two prints on 8?)
Thank you all.
-
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-
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Re: [Tutor] __getattr__(): Is this right?
> "Note that if the attribute is found through the normal mechanism, > __getattr__() is not called. (This is an intentional asymmetry between > __getattr__() and __setattr__().) This is done both for efficiency > reasons and because otherwise __setattr__() would have no way to > access other attributes of the instance." There you go, you are right and I am not. I guess because I don't actually set the attribute of self, I can intercept both the get and set. "Learn one new thing every day". Done. :-) Happy to help :) You may be interested in: __getattribute__ http://docs.python.org/ref/new-style-attribute-access.html That will get ALL requests. Read the warnings, though. - Tonight's top picks. What will you watch tonight? Preview the hottest shows on Yahoo! TV.___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] __getattr__(): Is this right? [w/ new code]
What did you try? What happened? What did you expect?
Kent
Narrowed things down a bit.
Given this class:
---
class sc(object):
def __init__(self, **kargs):
self.valid_props = [ 'foo', 'bar', 'baz' ]
for prop in self.valid_props:
if kargs.has_key(prop):
self.__setattr__(prop, kargs[prop])
def __getattr__(self,attr):
if attr in self.valid_props:
print "__getattr__ was called for %s" % attr
return 'n/a'
else:
raise AttributeError, attr
This is my in/output:
-
In [1]: some_string_a = 'foo'
In [2]: some_string_b = 'FOO'
In [3]: s = sc( foo=some_string_b )
In [4]: s.foo
Out[4]: 'FOO'
In [5]: eval('s.' + some_string_a)
Out[5]: 'FOO'
In [6]: s.__getattr__(some_string_a)
__getattr__ was called for foo
Out[6]: 'n/a'
In [7]: s.__getattr__('foo')
__getattr__ was called for foo
Out[7]: 'n/a'
In [8]: s.bar
__getattr__ was called for bar
__getattr__ was called for bar
Out[8]: 'n/a'
In [9]: s.__getattr__('bar')
__getattr__ was called for bar
Out[9]: 'n/a'
Here is what I expected:
--
Outputs 4 and 5 are fine.
Outputs 6 and 7 should have returned 'FOO'
Outputs 8 and 9 are fine. (But why two prints on 8?)
Thank you all.
-
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Re: [Tutor] __getattr__(): Is this right?
Eric Brunson <[EMAIL PROTECTED]> wrote: Allen Fowler wrote: > I seem to be having an issue with __getattr__() being called even if > the proporite already exists... I thought that this was not supposed > to happen. I think you've misunderstood. __getattr__() should always be called, it allows you to intercept and reimplement the behavior of a attribute lookup to suit your needs. Typically, my __getattrs__() look like this: See: http://docs.python.org/ref/attribute-access.html This would lead me to think not that way... "Note that if the attribute is found through the normal mechanism, __getattr__() is not called. (This is an intentional asymmetry between __getattr__() and __setattr__().) This is done both for efficiency reasons and because otherwise __setattr__() would have no way to access other attributes of the instance." - Building a website is a piece of cake. Yahoo! Small Business gives you all the tools to get online.___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] __getattr__(): Is this right?
I seem to be having an issue with __getattr__() being called even if the proporite already exists... I thought that this was not supposed to happen. Is there a typo somewhere, or I do i misunderstand things? class someclass(object): def __init__(self, **kargs): self.valid_props = [ 'foo', 'bar', 'baz' ] for prop in self.valid_props: if kargs.has_key(prop): self.__setattr__(prop, kargs[prop]) def __getattr__(self,attr): if attr in self.valid_props: # This print should throw an exception, # but it does not. It shows the value. print "Oh no.. This was not found: %s" % self.__dict__[attr] return 'n/a' else: raise AttributeError, attr - Boardwalk for $500? In 2007? Ha! Play Monopoly Here and Now (it's updated for today's economy) at Yahoo! Games.___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Exceptions: Logging TB and local variables?
Hi, My code looks like this: for item in bigset: self.__sub1(item) self.__sub2(item) self.__sub3(item) # the subX functions, in turn, use various 3rd party modules. Now, I would like to do this: for item in bigset: try: self.__sub1(item) self.__sub2(item) self.__sub3(item) except StandardError: # Log error and continue to next item in set. log_error_to_file() In the error log, I would like to record a stacktrace and various local variables that existed in subX at the time the Exception was thrown... (even though the actual exception may have been thrown from deep inside some 3rd party module that subX called) How should I do this? Am I barking up the right tree? Thank you, Allen - Need a vacation? Get great deals to amazing places on Yahoo! Travel. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
