[Tutor] Module webbrowser.os
Palanikumar Gopalakrishnan
palani at vahaitech.com
Thu Nov 3 02:43:45 EDT 2016
On Wed, Nov 2, 2016 at 7:36 AM, <tutor-request at python.org> wrote:
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> Today's Topics:
>
> 1. Re: Python code (Danny Yoo)
> 2. Re: implementing sed - termination error (cs at zip.com.au)
> 3. Module webbrowser.os (Palanikumar Gopalakrishnan)
> 4. Re: implementing sed - termination error (Peter Otten)
> 5. Re: Module webbrowser.os (Alan Gauld)
> 6. Re: Module webbrowser.os (Steven D'Aprano)
>
>
> ---------- Forwarded message ----------
> From: Danny Yoo <dyoo at hashcollision.org>
> To: Haley Sandherr <haleysandherr at gmail.com>
> Cc: Tutor at python.org
> Date: Tue, 1 Nov 2016 21:58:08 -0700
> Subject: Re: [Tutor] Python code
> On Nov 1, 2016 4:57 PM, "Haley Sandherr" <haleysandherr at gmail.com> wrote:
> >
> > Hello, I am new to python and need help with this question:
> >
> > Compose a function odd ( ) that takes three bool arguments and returns
> True if an odd number of arguments are True and False otherwise.
>
> Do you understand all of the terms in the question? Are there terms in the
> question that you don't know?
>
> Try a simpler, related problem if you are getting stuck: it may help point
> the way forward.
>
> For example, your original question has three arguments. Can you do the
> problem variation that just has one boolean argument? Call this odd1().
> You can see that it's like the original problem.
>
> If you can do this, try writing odd2(): a function that can deal with two
> arguments. Can you do this?
>
> What other similar functions have you seen so far?
>
> These questions are intended to help us calibrate our mental model of what
> you currently understand. Please tell us more do we can give you
> appropriate answers.
>
>
>
> ---------- Forwarded message ----------
> From: cs at zip.com.au
> To: bruce <badouglas at gmail.com>
> Cc: Python Tutor Mailing List <tutor at python.org>
> Date: Wed, 2 Nov 2016 16:22:21 +1100
> Subject: Re: [Tutor] implementing sed - termination error
> On 01Nov2016 20:18, bruce <badouglas at gmail.com> wrote:
>
>> Running a test on a linux box, with python.
>> Trying to do a search/replace over a file, for a given string, and
>> replacing the string with a chunk of text that has multiple lines.
>>
>> From the cmdline, using sed, no prob. however, implementing sed, runs
>> into issues, that result in a "termination error"
>>
>
> Just terminology: you're not "implementing sed", which is a nontrivial
> task that would involve writing a python program that could do everything
> sed does. You're writing a small python program to call sed to do the work.
>
> Further discussion below.
>
> The error gets thrown, due to the "\" of the newline. SO, and other
>> sites have plenty to say about this, but haven't run across any soln.
>>
>> The test file contains 6K lines, but, the process requires doing lots
>> of search/replace operations, so I'm interested in testing this method
>> to see how "fast" the overall process is.
>>
>> The following psuedo code is what I've used to test. The key point
>> being changing the "\n" portion to try to resolved the termination
>> error.
>>
>> import subprocess
>>
>> ll_="ffdfdfdfghhhh"
>> ll2_="12112121212121212"
>> hash="aaaaa"
>>
>> data_=ll_+"\n"+ll2_+"\n"+qq22_
>> print data_
>>
>
> Presuming qq22_ is not shown.
>
> cc='sed -i "s/'+hash+'/'+data_+'/g" '+dname
>> print cc
>> proc=subprocess.Popen(cc, shell=True,stdout=subprocess.PIPE)
>> res=proc.communicate()[0].strip()
>>
>
> There are two fairly large problems with this program. The first is your
> need to embed newlines in the replacement pattern. You have genuine
> newlines in your string, but a sed command would look like this:
>
> sed 's/aaaaa/ffdfdfdfghhhh\
> 12112121212121212\
> qqqqq/g'
>
> so you need to replace the newlines with "backslash and newline".
>
> Fortunately strings have a .replace() method which you can use for this
> purpose. Look it up:
>
> https://docs.python.org/3/library/stdtypes.html#str.replace
>
> You can use it to make data_ how you want it to be for the command.
>
> The second problem is that you're then trying to invoke sed by
> constructing a shell command string and handing that to Popen. This means
> that you need to embed shell syntax in that string to quote things like the
> sed command. All very messy.
>
> It is better to _bypass_ the shell and invoke sed directory by leaving out
> the "shell=True" parameter. All the command line (which is the shell) is
> doing is honouring the shell quoting and constructing a sed invocation as
> distinct strings:
>
> sed
> -i
> s/this/that/g
> filename
>
> You want to do the equivalent in python, something like this:
>
> sed_argv = [ 'sed', '-i', 's/'+hash+'/'+data_+'/g', dname ]
> proc=subprocess.Popen(sed_argv, stdout=subprocess.PIPE)
>
> See how you're now unconcerned by any difficulties around shell quoting?
> You're now dealing directly in strings.
>
> There are a few other questions, such as: if you're using sed's -i option,
> why is stdout a pipe? And what if hash or data_ contain slashes, which you
> are using in sed to delimit them?
>
> Hoping this will help you move forward.
>
> Cheers,
> Cameron Simpson <cs at zip.com.au>
>
>
>
> ---------- Forwarded message ----------
> From: Palanikumar Gopalakrishnan <palani at vahaitech.com>
> To: tutor at python.org
> Cc:
> Date: Wed, 2 Nov 2016 12:14:50 +0530
> Subject: [Tutor] Module webbrowser.os
> Hi Guys,
> I recently tested with some code , which open browser
>
> import webbrowser
> webbrowser.open("https://www.google.com")
>
> After that i want to experiment with webbrowser.os module, But dont know
> how to execute it.So I use dir(webbrowser.os) to find some details. Then i
> tried the following
>
> webbrowser.os(umask)
>
> But It retruns the following error
>
>
>
> *Traceback (most recent call last): File "<stdin>", line 1, in
> <module>NameError: name 'umask' is not defined*
>
>
>
>
>
> --
>
> *Warm Regards,*
>
> *Palanikumar Gopalakrishnan *[image: ✌]
> *Developer*
>
>
>
> ---------- Forwarded message ----------
> From: Peter Otten <__peter__ at web.de>
> To: tutor at python.org
> Cc:
> Date: Wed, 02 Nov 2016 09:21:45 +0100
> Subject: Re: [Tutor] implementing sed - termination error
> bruce wrote:
>
> > Hi
> >
> > Running a test on a linux box, with python.
> >
> > Trying to do a search/replace over a file, for a given string, and
> > replacing the string with a chunk of text that has multiple lines.
> >
> > From the cmdline, using sed, no prob. however, implementing sed, runs
> > into issues, that result in a "termination error"
> >
> > The error gets thrown, due to the "\" of the newline. SO, and other
> > sites have plenty to say about this, but haven't run across any soln.
> >
> > The test file contains 6K lines, but, the process requires doing lots
> > of search/replace operations, so I'm interested in testing this method
> > to see how "fast" the overall process is.
> >
> > The following psuedo code is what I've used to test. The key point
> > being changing the "\n" portion to try to resolved the termination
> > error.
>
> Here's a self-contained example that demonstrates that the key change is to
> avoid shell=True.
>
> $ cat input.txt
> foo
> alpha
> beta foo gamma
> epsilon
> foo zeta
> $ sed s/foo/bar\\nbaz/g input.txt
> bar
> baz
> alpha
> beta bar
> baz gamma
> epsilon
> bar
> baz zeta
> $ python3
> Python 3.4.3 (default, Sep 14 2016, 12:36:27)
> [GCC 4.8.4] on linux
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import subprocess
> >>> subprocess.call(["sed", "s/foo/bar\\nbaz/g", "input.txt"])
> bar
> baz
> alpha
> beta bar
> baz gamma
> epsilon
> bar
> baz zeta
> 0
>
> Both the shell and Python require you to escape, so if you use one after
> the
> other you have to escape the escapes; but with only one level of escapes
> and
> a little luck you need not make any changes between Python and the shell.
>
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Alan Gauld <alan.gauld at yahoo.co.uk>
> To: tutor at python.org
> Cc:
> Date: Wed, 2 Nov 2016 09:16:56 +0000
> Subject: Re: [Tutor] Module webbrowser.os
> On 02/11/16 06:44, Palanikumar Gopalakrishnan wrote:
> > After that i want to experiment with webbrowser.os module, But dont know
> > how to execute it.
>
> webbrowser.os seems to just be a link to the standard os module.
> So you should read the docs for os...and use the os module directly.
>
> > So I use dir(webbrowser.os) to find some details. Then i
> > tried the following
> >
> > webbrowser.os(umask)
> >
> > But It retruns the following error
> >
> > *Traceback (most recent call last): File "<stdin>", line 1, in
> > <module>NameError: name 'umask' is not defined*
>
> I'm not sure why because it works for me in both Python 2.7 and 3.4.
> Which OS are you using? And which Python version?
>
> But note that umask is a function so
>
> webbrowser.os(umask)
>
> returns a function reference. To get the umask value you must
> supply one:
>
> webbrowser.os(umask(0x777))
>
> And the returned value will be the current umask() (Which you
> should store and restore when finished with the new umask)
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
>
>
>
> ---------- Forwarded message ----------
> From: "Steven D'Aprano" <steve at pearwood.info>
> To: tutor at python.org
> Cc:
> Date: Wed, 2 Nov 2016 22:36:40 +1100
> Subject: Re: [Tutor] Module webbrowser.os
> On Wed, Nov 02, 2016 at 12:14:50PM +0530, Palanikumar Gopalakrishnan wrote:
> > Hi Guys,
> > I recently tested with some code , which open browser
> >
> > import webbrowser
> > webbrowser.open("https://www.google.com")
> >
> > After that i want to experiment with webbrowser.os module,
>
> webbrowser.os is just the os module.
>
> https://docs.python.org/2/library/os.html
> https://docs.python.org/3/library/os.html
>
> When a module imports another module, say:
>
> import os
>
> then "os" becomes a top level name, available as webbrowser.os. But you
> shouldn't use it. Just do "import os" and then use "os" on its own.
>
>
>
> --
> Steve
>
>
> _______________________________________________
> Tutor maillist - Tutor at python.org
> https://mail.python.org/mailman/listinfo/tutor
>
>
Hi Alan,
My python version is *2.7. *I tried the following but it not
working , Returns same error message
webbrowser.os(umask)
webbrowser.os(umask(0x777))
--
*Warm Regards,*
*Palanikumar Gopalakrishnan *[image: ✌]
*Developer*
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