As far as sending the contents of stderr to a tmp file...hmmm, i will try that. My only concern is, many of these systems run live demo feeds for many days...10+. Im afraid the file will fill up very quickly and present problems.
Stderr=PIPE causes the terminal to hang. I can not wait for the process to terminate, i need to read stderr as it is being fed data.. Would fifos be of any use here? I will research the tempfile module. Bo > On Aug 27, 2014, at 7:38 PM, tutor-requ...@python.org wrote: > > Send Tutor mailing list submissions to > tutor@python.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://mail.python.org/mailman/listinfo/tutor > or, via email, send a message with subject or body 'help' to > tutor-requ...@python.org > > You can reach the person managing the list at > tutor-ow...@python.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Tutor digest..." > > > Today's Topics: > > 1. Re: Python Programming (Alan Gauld) > 2. Re: simple unicode question (Alan Gauld) > 3. Interacting with stderr (Crush) > 4. Re: Interacting with stderr (Cameron Simpson) > 5. Re: debug and execute python code in Mac (Alan Gauld) > 6. Re: Interacting with stderr (Alan Gauld) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 27 Aug 2014 19:57:12 +0100 > From: Alan Gauld <alan.ga...@btinternet.com> > To: tutor@python.org > Subject: Re: [Tutor] Python Programming > Message-ID: <ltl9m8$m45$1...@ger.gmane.org> > Content-Type: text/plain; charset=windows-1252; format=flowed > >> On 27/08/14 14:40, Jake wrote: >> To whom it may concern, >> My name is Jake and I have recently started the GCSE computing course with >> school. > >> answera = input() >> if answera == ["Oslo" or "oslo"]: > > This doesn't do what you think it does. > > ["Oslo" or "oslo"] is a list > > "Oslo" or "oslo" is the content of the list and > is a boolean expression which evaluates to True. > (Each non-empty string is considered True by Python) > > So your 'if' line looks to Python like: > > if answera == [True]: > > But answera is a string so it will never equal a list > with a single boolean value so you go to the else > clause. > > A better way to do what you want is to convert the input > to lowercase using the string lower() method and compare > that to the string you want, like so: > > if answera.lower() == "oslo": > > If you need to check multiple possible answers you can use > a list of strings and the 'in' operator like this: > > if answera.lower() in ['amsterdam', 'london', 'oslo']: > > HTH > -- > Alan G > Author of the Learn to Program web site > http://www.alan-g.me.uk/ > http://www.flickr.com/photos/alangauldphotos > > > > ------------------------------ > > Message: 2 > Date: Wed, 27 Aug 2014 20:09:36 +0100 > From: Alan Gauld <alan.ga...@btinternet.com> > To: tutor@python.org > Subject: Re: [Tutor] simple unicode question > Message-ID: <ltladg$uva$1...@ger.gmane.org> > Content-Type: text/plain; charset=utf-8; format=flowed > > On 27/08/14 15:57, Albert-Jan Roskam wrote: > >>> if *fewer* than 1 in 10 operations will raise an exception, then use >>> try...except; but if *more* than 1 in 10 operations will raise an >>> exception, and it is safe to do so, then LBYL may be appropriate. >> >> >> Thanks a lot, Steven! This kind of stuff should be in a book. > > It is in lots of books but they aren't Python books; they are generic > software engineering books. Because this is not really a language > specific type design issue, its general software design. > >> Do you know of any real life examples where the code is written >> in such a way that it could switch from AFTP to LBYL > > It would be very unlikely since it would almost always be a case of > premature optimisation. You would need to be inside a very tight loop to > make that kind of optimisation worthwhile in real world scenarios. > (And the cost of evaluating it would probably outweigh any gains.) > > Much more important is to make the code correct and maintainable than to > worry about slight performance issues before they are a proven issue. > Building those kind of self modifying control flows makes code much more > error prone and difficult to modify. > > The vast majority of performance issues in software are to do with > blockages in IO processing(network, disk access, human input, etc) > or database processing (big data or complex searches) or in traversing > complex/deep data structures. Very few real-world performance issues > are related to simple code execution issues. > > -- > Alan G > Author of the Learn to Program web site > http://www.alan-g.me.uk/ > http://www.flickr.com/photos/alangauldphotos > > > > ------------------------------ > > Message: 3 > Date: Wed, 27 Aug 2014 18:45:41 -0400 > From: Crush <crushe...@gmail.com> > To: "tutor@python.org" <tutor@python.org> > Subject: [Tutor] Interacting with stderr > Message-ID: <77745ca4-8f7d-410c-800d-f0a3c711d...@gmail.com> > Content-Type: text/plain; charset="us-ascii" > > Hello, it has been a while and I hope I am sending to the correct email. > > How would I go about running a conditional statement against the contents of > stderr. For instance, if "blah blah blah" is in stderr do X, else do Y. > > CODE: SELECT ALL > > #!/usr/bin/env python > import subprocess > from subprocess import PIPE > i = 0 > while i < 10: > p = subprocess.call("avconv -v verbose -re -analyzeduration 1000 -i > http://localhost:6498/ms2/1382097438004/0MediaPlayer+0+/octoshape+hVV+octolive.americaone.com+V+aone+V+live+V+ONECONNXT_DEMO1_HD_flv/aoneliveONECONNXTDEMO1HDflv > -c:v rawvideo -c:a pcm_s16le -ar 48000 -f nut - | ./bmdplay -m 12 -f > pipe:0", shell=True) > i += 1 > if i == 10: > print "Gave up" > > > The above code works and I get no tracebacks, however I need to add to it and > check the contents of stderr. Avconv by default sends the audio and video to > stdout, which then sends the signal to a capture card in the machine. Avconv > is sending the status of the broadcasted signal i.e. frames, time, fps, etc. > to stderr, which is displayed in the terminal. > > Bo > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://mail.python.org/pipermail/tutor/attachments/20140827/05ab01b4/attachment-0001.html> > > ------------------------------ > > Message: 4 > Date: Thu, 28 Aug 2014 08:55:39 +1000 > From: Cameron Simpson <c...@zip.com.au> > To: "tutor@python.org" <tutor@python.org> > Subject: Re: [Tutor] Interacting with stderr > Message-ID: <20140827225539.ga55...@cskk.homeip.net> > Content-Type: text/plain; charset=us-ascii; format=flowed > >> On 27Aug2014 18:45, Crush <crushe...@gmail.com> wrote: >> Hello, it has been a while and I hope I am sending to the correct email. >> >> How would I go about running a conditional statement against the contents of >> stderr. For instance, if "blah blah blah" is in stderr do X, else do Y. >> >> >> #!/usr/bin/env python >> import subprocess >> from subprocess import PIPE >> i = 0 >> while i < 10: >> p = subprocess.call("avconv -v verbose -re -analyzeduration 1000 -i >> http://localhost:6498/ms2/1382097438004/0MediaPlayer+0+/octoshape+hVV+octolive.americaone.com+V+aone+V+live+V+ONECONNXT_DEMO1_HD_flv/aoneliveONECONNXTDEMO1HDflv >> -c:v rawvideo -c:a pcm_s16le -ar 48000 -f nut - | ./bmdplay -m 12 -f >> pipe:0", > shell=True) >> i += 1 >> if i == 10: >> print "Gave up" >> >> The above code works and I get no tracebacks, however I need to add to it and >> check the contents of stderr. Avconv by default sends the audio and video to >> stdout, which then sends the signal to a capture card in the machine. Avconv >> is sending the status of the broadcasted signal i.e. frames, time, fps, etc. >> to stderr, which is displayed in the terminal. > > Send stderr to a file, using a parameter like: > > stderr=open('stderr.out', 'w') > > in your call() call. Then open 'stderr.out' and look for the relevant > information. > > Obviously in a "real" program you'd take care to make that a temporary file > with a unique name using the functions from the "tempfile" module, etc. But > make it work first. > > Cheers, > Cameron Simpson <c...@zip.com.au> > > The Few. The Proud. The Politically Incorrect. - Steve Masticola > > > ------------------------------ > > Message: 5 > Date: Thu, 28 Aug 2014 00:31:08 +0100 > From: Alan Gauld <alan.ga...@btinternet.com> > To: tutor@python.org > Subject: Re: [Tutor] debug and execute python code in Mac > Message-ID: <ltlpns$sic$1...@ger.gmane.org> > Content-Type: text/plain; charset=windows-1252; format=flowed > > On 27/08/14 13:47, Patrick Thunstrom wrote: > >>> I do not like the cmd/terminal execution. Thanks ! >> >> I don't know many ways to debug code that don't involve the terminal >> in some fashion. Even with a good IDE you're going to have a terminal >> built in for output. > > Not necessarily. A text display widget within a GUI is very different > from a text based terminal. Many graphical debuggers display data > structures in a hierarchical model where you can expand/close the > various levels etc. > > But I think the OP is specifically wanting to avoid command prompts. The > question is: Does he mean all prompts (including > Python's) or just the OS prompt? If its all prompts then it gets > much harder to find an IDE that will suit. > > > -- > Alan G > Author of the Learn to Program web site > http://www.alan-g.me.uk/ > http://www.flickr.com/photos/alangauldphotos > > > > ------------------------------ > > Message: 6 > Date: Thu, 28 Aug 2014 00:38:09 +0100 > From: Alan Gauld <alan.ga...@btinternet.com> > To: tutor@python.org > Subject: Re: [Tutor] Interacting with stderr > Message-ID: <ltlq51$v4s$1...@ger.gmane.org> > Content-Type: text/plain; charset=windows-1252; format=flowed > >> On 27/08/14 23:45, Crush wrote: >> Hello, it has been a while and I hope I am sending to the correct email. >> >> How would I go about running a conditional statement against the >> contents of stderr. For instance, if "blah blah blah" is in stderr do X, >> else do Y. > > You can access stderr just like you access stdout. > The recommended way is via communicate: > > --------------- > Popen.communicate(input=None, timeout=None) > > Interact with process: Send data to stdin. Read data from stdout and > stderr, until end-of-file is reached. Wait for process to terminate. The > optional input argument should be data to be sent to the child process, > or None, if no data should be sent to the child. The type of input must > be bytes or, if universal_newlines was True, a string. > > communicate() returns a tuple (stdoutdata, stderrdata). > > Note that if you want to send data to the process?s stdin, you need to > create the Popen object with stdin=PIPE. Similarly, to get anything > other than None in the result tuple, you need to give stdout=PIPE and/or > stderr=PIPE too. > -------------------- > > HTH > -- > Alan G > Author of the Learn to Program web site > http://www.alan-g.me.uk/ > http://www.flickr.com/photos/alangauldphotos > > > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > Tutor maillist - Tutor@python.org > https://mail.python.org/mailman/listinfo/tutor > > > ------------------------------ > > End of Tutor Digest, Vol 126, Issue 69 > ************************************** _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
