[Tutor] Tutor Digest, Vol 87, Issue 120
priyesh raj
raj.priyesh at gmail.com
Tue May 31 00:44:52 CEST 2011
Hi,
To excute a "Java" command, using os.system, you need to either give
absolute path, or you need to append the path in system variable. For
example,
1. Either os.system('/usr/bin/java')
or
2. import sys
sys.path.append('/usr/bin')
os.system('java')
Hope this helps.
Regards,
Priyesh
On Tue, May 31, 2011 at 3:51 AM, <tutor-request at python.org> wrote:
> Send Tutor mailing list submissions to
> tutor at python.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://mail.python.org/mailman/listinfo/tutor
> or, via email, send a message with subject or body 'help' to
> tutor-request at python.org
>
> You can reach the person managing the list at
> tutor-owner at python.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Tutor digest..."
>
>
> Today's Topics:
>
> 1. Finding error from os.system(cmd) (Kann Vearasilp)
> 2. Re: Finding error from os.system(cmd) (Alexandre Conrad)
> 3. Re: Finding error from os.system(cmd) (Marilyn Davis)
> 4. Re: Importing classes when needed (Alan Gauld)
> 5. Re: Importing classes when needed (Marilyn Davis)
> 6. Re: Importing classes when needed (Steven D'Aprano)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 30 May 2011 14:28:49 +0200
> From: Kann Vearasilp <vearasilp at gmail.com>
> To: Python Tutor <tutor at python.org>
> Subject: [Tutor] Finding error from os.system(cmd)
> Message-ID: <BANLkTim8C+cTraAUu+F0n1hy=-GL5i+sFQ at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Dear all,
>
> I tried using python to execute some external java program in my code.
> My problem is the os.system(cmd) was not working properly while
> executing 'java' from terminal worked just fine. I am not sure what is
> wrong here. Is there a way to print out/detect error in my code for
> this case?
>
> >>>>
>
> 1 import os
> 2
> 3 def create_image():
> 4 path = os.path.abspath('tmp/medusa')
> 5 medusa = os.path.abspath('mirnaworkbench/Medusa/Medusa.jar')
> 6 cmd = str('java -cp ' + medusa + '
> medusa.batchoperations.BatchOperations ' + path)
> 7 os.system(cmd)
>
> >>>>
>
> Thanks,
>
> Kann
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 30 May 2011 09:46:04 -0700
> From: Alexandre Conrad <alexandre.conrad at gmail.com>
> To: Kann Vearasilp <vearasilp at gmail.com>
> Cc: Python Tutor <tutor at python.org>
> Subject: Re: [Tutor] Finding error from os.system(cmd)
> Message-ID: <BANLkTikratSp1gey-DvzAc-S0xrma=cxsQ at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> Hi Kann,
>
> I haven't looked at your problem closely but you might need to
> explicitly tell Python where to output stderr/stdout. I just ran
> os.system('ls -al') on my Linux box and it seems to print both
> stderr/stdout to my terminal. The return value is the return code of
> the process (might be different on another OS though).
>
> As I hint you might want to know that the "subprocess" module is meant
> to replace many Python functions that spawn processes, such as
> os.system(). The subprocess module might be better documented with
> examples:
>
> http://docs.python.org/library/subprocess.html
>
> Only if you are running Python 2.7 (or 3.x I believe), the
> subprocess.check_output() function might be useful to you.
>
> HTH,
>
> 2011/5/30 Kann Vearasilp <vearasilp at gmail.com>:
> > Dear all,
> >
> > I tried using python to execute some external java program in my code.
> > My problem is the os.system(cmd) was not working properly while
> > executing 'java' from terminal worked just fine. I am not sure what is
> > wrong here. Is there a way to print out/detect error in my code for
> > this case?
> >
> >>>>>
> >
> > ?1 import os
> > ?2
> > ?3 def create_image():
> > ?4 ? ? path = os.path.abspath('tmp/medusa')
> > ?5 ? ? medusa = os.path.abspath('mirnaworkbench/Medusa/Medusa.jar')
> > ?6 ? ? cmd = str('java -cp ' + medusa + '
> > medusa.batchoperations.BatchOperations ' + path)
> > ?7 ? ? os.system(cmd)
> >
> >>>>>
> >
> > Thanks,
> >
> > Kann
> > _______________________________________________
> > Tutor maillist ?- ?Tutor at python.org
> > To unsubscribe or change subscription options:
> > http://mail.python.org/mailman/listinfo/tutor
> >
>
>
>
> --
> Alex | twitter.com/alexconrad
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 30 May 2011 09:48:04 -0700 (PDT)
> From: "Marilyn Davis" <marilyn at pythontrainer.com>
> To: tutor at python.org
> Subject: Re: [Tutor] Finding error from os.system(cmd)
> Message-ID:
> <47524.67.169.189.143.1306774084.squirrel at mail.tigertech.net>
> Content-Type: text/plain;charset=utf-8
>
> Hi Kann,
>
> So you are saying that you printed your command, then ran it at the
> terminal prompt, and it ran ok?
>
> You might want to look at the subprocess library so that you can collect
> stderr from the process. The online documentation is great, with lots of
> examples.
>
> BTW, on your line 6, you str(some-stuff-that-is-already-a-str), which is a
> waste, and a little confusion for your reader.
>
> I hope you find some help in these suggestions.
>
> Marilyn Davis
>
>
> On Mon, May 30, 2011 5:28 am, Kann Vearasilp wrote:
>
> > Dear all,
> >
> >
> > I tried using python to execute some external java program in my code.
> > My problem is the os.system(cmd) was not working properly while
> > executing 'java' from terminal worked just fine. I am not sure what is
> > wrong here. Is there a way to print out/detect error in my code for this
> > case?
> >
> >>>>>
> >
> > 1 import os
> > 2
> > 3 def create_image():
> > 4 path = os.path.abspath('tmp/medusa')
> > 5 medusa = os.path.abspath('mirnaworkbench/Medusa/Medusa.jar')
> > 6 cmd = str('java -cp ' + medusa + '
> > medusa.batchoperations.BatchOperations ' + path) 7 os.system(cmd)
> >
> >
> >>>>>
> >
> > Thanks,
> >
> >
> > Kann
> > _______________________________________________
> > Tutor maillist - Tutor at python.org
> > To unsubscribe or change subscription options:
> > http://mail.python.org/mailman/listinfo/tutor
>
>
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 30 May 2011 21:57:27 +0100
> From: "Alan Gauld" <alan.gauld at btinternet.com>
> To: tutor at python.org
> Subject: Re: [Tutor] Importing classes when needed
> Message-ID: <is10bo$a38$1 at dough.gmane.org>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
>
> "Alexandre Conrad" <alexandre.conrad at gmail.com> wrote
>
> >> Why not use the os functions to read the file names
> >> dynamically and build the list that way? Provided
> >> the files use a standard naming scheme you don't
> >> need to change the init code.
> >
> > I wouldn't do that. If Timo adds non-parser modules in that
> > directory
> > (say some utils.py file for all parsers to use), then you have to
> > maintain a list of excluded files
>
> I did say he would have to use a naming convention and
> that in turn implies the use of glob to filter the names returned.
> But I agree it has risks but then, so does relying on
> always editing init.py
>
> I just prefer to avoid introducing hard to remember
> maintenance tasks when I can do it automatically,
> but of course you need to remember the naming convention.
> But hopefully a quick 'ls' will do that for you...
>
> Alan G.
>
>
>
>
> ------------------------------
>
> Message: 5
> Date: Mon, 30 May 2011 14:57:24 -0700 (PDT)
> From: "Marilyn Davis" <marilyn at pythontrainer.com>
> To: "Alan Gauld" <alan.gauld at btinternet.com>
> Cc: tutor at python.org
> Subject: Re: [Tutor] Importing classes when needed
> Message-ID:
> <55862.67.169.189.143.1306792644.squirrel at mail.tigertech.net>
> Content-Type: text/plain;charset=utf-8
>
> If we are coding via a vote, I'd be with Alan.
>
> If Timo adds non-parser modules, and they get through his glob filter,
> then surely his code will break with a nice error statement and that would
> remind him of his convention.
>
> Or maybe it would just give a verbose report and go on to the next file.
>
> Marilyn
>
> On Mon, May 30, 2011 1:57 pm, Alan Gauld wrote:
>
> > "Alexandre Conrad" <alexandre.conrad at gmail.com> wrote
> >
> >
> >>> Why not use the os functions to read the file names
> >>> dynamically and build the list that way? Provided the files use a
> >>> standard naming scheme you don't need to change the init code.
> >>
> >> I wouldn't do that. If Timo adds non-parser modules in that
> >> directory (say some utils.py file for all parsers to use), then you have
> >> to maintain a list of excluded files
> >
> > I did say he would have to use a naming convention and
> > that in turn implies the use of glob to filter the names returned. But I
> > agree it has risks but then, so does relying on always editing init.py
> >
> > I just prefer to avoid introducing hard to remember
> > maintenance tasks when I can do it automatically, but of course you need
> to
> > remember the naming convention. But hopefully a quick 'ls' will do that
> > for you...
> >
> > Alan G.
> >
> >
> >
> > _______________________________________________
> > Tutor maillist - Tutor at python.org
> > To unsubscribe or change subscription options:
> > http://mail.python.org/mailman/listinfo/tutor
>
>
>
>
> ------------------------------
>
> Message: 6
> Date: Tue, 31 May 2011 08:21:36 +1000
> From: Steven D'Aprano <steve at pearwood.info>
> To: "tutor at python.org" <Tutor at python.org>
> Subject: Re: [Tutor] Importing classes when needed
> Message-ID: <4DE41870.8020909 at pearwood.info>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Timo wrote:
> > Hello all,
> >
> > I have a question about how this is done the best way.
> >
> > In my project I have a folder with multiple file parsers, like this:
> > - src
> > -- main.py
> > -- parsers
> > --- __init__.py
> > --- parser1.py
> > --- parser2.py
>
> This gives you a stand-alone module called "main.py", and a separate
> package called "parsers". Is that intended?
>
> I might think about putting this in a single package, perhaps like this:
>
>
> - src
> -- my_application
> -- __init__.py
> -- __main__.py
> -- parsers
> --- __init__py
> --- parser1.py
> --- parser2.py
>
>
> Now my_application is treated as a single package, containing a
> sub-package my_application.parsers.
>
> The purpose of the __main__.py is that when you call the package from
> the command line, like this:
>
> python -m my_application
>
> the code inside __main__.py is executed.
>
>
> > The parsers just contain a class which do the work.
>
>
> Keep in mind that this is Python, not Java, and it's not compulsory to
> have one class per file. If the classes are small enough you are
> encouraged to put them in the one file.
>
> Particularly if you use inheritance to delegate most of the work to a
> single parent class, something like this made up example:
>
> from parsers import Parser1
>
> class Parser2(Parser1):
> def parse(self, text):
> words = super(Parser2, self).parse(text)
> words = [s.lower() for s in words]
> return words
>
>
>
> > When the user clicks a button, I want to show all available parsers and
> > use the choosen one when the user clicks "ok".
> > Is it ok to place the following code in the __init__.py?
> > from parser1 import Parser1
> > from parser2 import Parser2
> > def get_parsers():
> > return [Parser1(), Parser2()]
>
> Certainly. You can have any code you like in __init__.py.
>
>
> > If so, is it ok to do a get_parsers() everytime the user clicks a
> > button? Because that will initialize the parsers over and over again,
> > right?
>
> Is that a problem?
>
> If you prefer to always use the same two parsers, do this instead:
>
> import parser1
> import parser2
>
> PARSERS = tuple(p() for p in (parser1, parser2))
>
>
> Then instead of calling get_parsers(), just use PARSERS.
>
>
>
> --
> Steven
>
>
>
> ------------------------------
>
> _______________________________________________
> Tutor maillist - Tutor at python.org
> http://mail.python.org/mailman/listinfo/tutor
>
>
> End of Tutor Digest, Vol 87, Issue 120
> **************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/tutor/attachments/20110531/84c33e05/attachment-0001.html>
More information about the Tutor
mailing list