[Tutor] static variables - lock/semaphore
hi i have a program that is run on a website, and as it is run from a website, it can be called more than once and hence could end up corrupting db/data is there a way to use some sort of semaphore or lock so that it is not accessed simultaneously the problem is it can be done with static variables in C but how is it done in python thanks a lot __ 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] static variables - lock/semaphore
i have a program that is run on a website, and as it is run from a website, it can be called more than once and hence could end up corrupting db/data is there a way to use some sort of semaphore or lock so that it is not accessed simultaneously There are ways of doing this in Python but if you are using a relational database for the data its usually easier to apply row level locking at the database level. the problem is it can be done with static variables in C but how is it done in python It could be done with a global variable in Python in the same way but there are other solutions based around threads which have explicit locks etc. For a web application using Python threads would probably be a good bet. But you may find the whole problem simplified by adopting a web framework such as TurboGears which will take care of a lot of these kinds of issues for you - but with a bit of a learning curve. But if you have several web apps to build I'd seriously consider this route. Alan Gauld Author of the Learn to Program web site http://www.freenetpages.co.uk/hp/alan.gauld ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] python debugger
Hi, guys,I have a small problem with python's debugger. I don't know how can I debugg a script through this debugger.Can you tell me?Thank you very much___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] static variables - lock/semaphore
anil maran wrote: hi i have a program that is run on a website, and as it is run from a website, it can be called more than once and hence could end up corrupting db/data is there a way to use some sort of semaphore or lock so that it is not accessed simultaneously the problem is it can be done with static variables in C but how is it done in python If you are using a database for storage you should learn how to use the transactional features of the database. They are designed to let you control what happens when multiple users access the database at the same time. To protect access to other kinds of data look at threading.Lock and RLock. Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving output in a text file (fwd)
[forwarding to Tutor] -- Forwarded message -- Date: Sat, 01 Jul 2006 13:58:47 +0400 From: Hafsa raza [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: [Tutor] saving output in a text file Thank you for the quick reply. Let me put my question in a more clearer way for you. If we want to create a text file and write some text into it we use the following command in Python: myfile = open(test.txt,w)?xml:namespace prefix = o ns = urn:schemas-microsoft-com:office:office / myfile.write(hello world) But what if instead of writing the text 'hello world', i want to write the output returned by a regular expression pattern, into the text file, how would we specify that in the write command. Regards, Hafsa From: Danny Yoo [EMAIL PROTECTED] To: Hafsa raza [EMAIL PROTECTED] CC: tutor@python.org Subject: Re: [Tutor] saving output in a text file Date: Fri, 30 Jun 2006 15:04:41 -0700 (PDT) def double(s): double: string - string doubles up the input string s. return s + s Gaah. Typos. My apologies. Here's a correction to double() def double(s): double: string - string Doubles up the input string s. For example, double(abc) should return abcabc. return s + s Would you be able to write a program that takes hello world, runs it through double(), and writes out hello worldhelloworld to disk? I meant to say that the expected content of the file should be: hello worldhello world My apologies; I rushed that message too quickly. FREE pop-up blocking with the new MSN Toolbar MSN Toolbar Get it now! ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] saving output in a text file (fwd)
If we want to create a text file and write some text into it we use the following command in Python: myfile = open(test.txt,w)?xml:namespace prefix = o ns = urn:schemas-microsoft-com:office:office / myfile.write(hello world) But what if instead of writing the text 'hello world', i want to write the output returned by a regular expression pattern, into the text file, how would we specify that in the write command. Just as a disclaimer: I am doing my utmost not to give out The Answer here. So if it sounds like I'm not being very direct, that's precisely because you have a good intuition. *grin* I'm trying to poke at the source of the problem, and not the immediate side effects. You still haven't tackled my initial question about: def double(s): double: string - string Doubles up the input string s. For example, double(abc) should return abcabc. return s + s Would you be able to write a program that takes hello world, runs it through double(), and writes out hello worldhello world to disk? Can you try this mini-problem first? What you've done doesn't touch on the question: would you know how to use double() as a part of the write()? Note that this is just a variation of your original question, replacing the regex part with the use of a helper function. It seems like this should be even easier than the problem you're having now. Here's why I'm asking this: if you're getting stuck at this point too, then I'll assume that the problem is that you are unfamiliar with using helper functions and function composition. Then the group as a whole can help you with that, since that's a fundamental programming skill that you'll want to develop. But if you can do the mini-exercise, then the focus shifts to the use of regular expressions, and things become much easier, since it'll mean that you're not familiar with the regex API. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
