Re: Config ConfigParser
On 2013-03-06, Chris Angelico ros...@gmail.com wrote: On Wed, Mar 6, 2013 at 2:31 PM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: What configuration settings does your podcast catcher software need? What makes you think it needs any? Don't over-engineer your application from the start. Begin with the simplest thing that works, and go from there. Agreed. The way I generally do these things is to simply gather the config entries into a block of literal assignments at the top of the program: host = ftp port = 21 proxy = 192.168.0.3:81 user = transfers password = secret I find it useful to stuff my config info in a class object; It is prettier than ALLCAPS, and also makes it simple to create and use new configurations without erasing or commenting out the old one. class Config: host = ftp port = 21 proxy = 192.168.0.3:81 user = transfers password = secret How much to engineer stuff is up to you. -- Neil Cerutti -- http://mail.python.org/mailman/listinfo/python-list
Config ConfigParser
I'm curious about using configuration files. Can someone tell me how they are used? I'm writing a podcast catcher and would like to set up some default configurations, e.g. directory, etcOther than default directory, what are some of the things that are put in a configuration file? They don't seem to teach you this kind of stuff in school. :( Thanks! -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
On 2013-03-05 12:09, Chuck wrote: I'm curious about using configuration files. Can someone tell me how they are used? I'm writing a podcast catcher and would like to set up some default configurations, e.g. directory, etcOther than default directory, what are some of the things that are put in a configuration file? Just looking at my hpodder config file, you can have all sorts of things in here. You might have a root folder, but then each feed could be configured to a particular sub-folder. You might have a cache location you download to, and only move them to the final destination after they've downloaded completely. You might have some check more frequently than others. You might have it execute an external utility (such as id3v2) to transform various ID3 information based on information in the feed. If you're downloading in multiple threads, you might have specify the number of threads it can use. If you are using curl under the covers, you might limit the transfer-rate so it doesn't suck up your bandwidth. If you display anything, you might allow for suppressing the display, formatting that display, or controlling whether it uses color. If you track download errors, you might specify how many failures constitute a don't bother retrying this item or how many days/hours you need to wait until you actually retry. You can even have it act as your data-store for holding the URLs to the RSS feeds, perhaps a readable name (to override what's in the feed), along with formatting. So a more complex .ini might look something like [general] root=/home/chuck/Music/Podcasts cache=/tmp/podchuck threads=4 rate=50k color=auto [feed http://feeds.5by5.tv/webahead;] display-name=The Web Ahead location=%(root)s/WebAhead/$FILENAME transform=id3v2 -a WebAhead -t $EPTITLE $FILENAME [feed http://www.radiolab.org/feeds/podcast;] location=/path/to/someplace/else/$FILENAME transform=id3v2 -a Radio Lab -t $EPTITLE $FILENAME -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
Thanks Tim! So much stuff I haven't thought of before. Out of curiosity, what's the benefit of caching the download, instead of downloading to the final destination? So much stuff they never teach you school.So much theory not enough practice. :( -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
On 2013-03-05 15:58, Chuck wrote: Thanks Tim! So much stuff I haven't thought of before. Out of curiosity, what's the benefit of caching the download, instead of downloading to the final destination? If your connection gets interrupted, the server goes down, etc, you have a partial download. If you've put it directly in the download path, your other programs see this partial download. However if your program can resume the download where it left off, once it's completed successfully, it can atomically move the file to your download location. Thus your other programs only ever see all-or-nothing in the download directory. -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
On Tue, 05 Mar 2013 12:09:38 -0800, Chuck wrote: I'm curious about using configuration files. Can someone tell me how they are used? I'm writing a podcast catcher and would like to set up some default configurations, e.g. directory, etcOther than default directory, what are some of the things that are put in a configuration file? They don't seem to teach you this kind of stuff in school. :( I think that you are doing this backwards. You shouldn't start with a question: I want a configuration file! What should I put in it? and then try to invent a need for configuration settings to put in the file. You start with the need, and end with the conclusion: I need these configuration settings. I'll put them in a config file. What configuration settings does your podcast catcher software need? What makes you think it needs any? Don't over-engineer your application from the start. Begin with the simplest thing that works, and go from there. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
On Tue, 05 Mar 2013 18:15:20 -0600, Tim Chase wrote: On 2013-03-05 15:58, Chuck wrote: Thanks Tim! So much stuff I haven't thought of before. Out of curiosity, what's the benefit of caching the download, instead of downloading to the final destination? If your connection gets interrupted, the server goes down, etc, you have a partial download. If you've put it directly in the download path, your other programs see this partial download. However if your program can resume the download where it left off, once it's completed successfully, it can atomically move the file to your download location. Thus your other programs only ever see all-or-nothing in the download directory. That's not really a *cache* though. Personally, I find programs that do that sort of cleverness annoying rather than helpful. More often than not, they are buggy and fail to clean up after themselves if the download is interrupted, so the secret download directory ends up filled with junk: cat-video27~ cat-video27-1~ cat-video27-2~ cat-video27-3~ sort of thing. Another problem with this tactic is that it makes it unnecessarily difficult to watch progress of the download, except via the application's official user interface. (If it gives you any interface for watching download progress, which is may not.) You have to locate the secret download directory, work out what file name the app is using for the temporary file (many apps obfuscate the file name), then watch that file grow until it suddenly disappears, at which point you then have to change directories to see if it reappeared where you actually wanted it to be, or was just deleted by something else. A third problem: instead of having to worry about having enough disk space in one location, now you have to worry about having enough disk space in *two* locations. I've even see a program download a large file into the temp location, *unsuccessfully* try to copy it into the final location, then delete the temp version. Yet another problem: websites sometimes lie about the size of some files. So when you download them, the actual file ends (say) one byte short of what the webserver claims. There's nothing wrong with the file, it is actually complete, or at least recoverable (many formats, like JPEG, are remarkably resistant to damage), but your app will think it never completes and either never move it to the final destination, or worse, keep trying to download it over and over and over again. Finally, moving from the temp directory to the final location is not necessarily an atomic operation. If it crosses file system boundaries, it is a two-step process. I think that the KISS principle applies here. If the user tells your app to download in some location, your app should download in that location. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
On Wed, Mar 6, 2013 at 2:31 PM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: What configuration settings does your podcast catcher software need? What makes you think it needs any? Don't over-engineer your application from the start. Begin with the simplest thing that works, and go from there. Agreed. The way I generally do these things is to simply gather the config entries into a block of literal assignments at the top of the program: host = ftp port = 21 proxy = 192.168.0.3:81 user = transfers password = secret From there, it's easy to decide whether to make them into command-line parameters, a parseable config file, an importable Python script (from config import * is an easy and simple way to make that one), or whatever. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
I guess my question was more what is a config.file why/how do I use one. Thanks -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
On Wed, Mar 6, 2013 at 3:07 PM, Chuck galois...@gmail.com wrote: I guess my question was more what is a config.file why/how do I use one. Thanks In its simplest form, a config file is one way to change a program's behaviour without editing the code. They're helpful when you want to be able to run the same program in different ways, or when you want to let someone else change what the program does without having to edit code (and without the changes getting overwritten by a program update). There are innumerable file formats that can be used. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
On Wed, 06 Mar 2013 15:19:53 +1100, Chris Angelico wrote: On Wed, Mar 6, 2013 at 3:07 PM, Chuck galois...@gmail.com wrote: I guess my question was more what is a config.file why/how do I use one. Thanks In its simplest form, a config file is one way to change a program's behaviour without editing the code. I don't think that's quite right, because your code has to be changed to read the data from the configuration file in the first place. It doesn't just happen by magic. Essentially, a configuration file is a file that holds configuration data. That data could be anything that makes sense for your program, but you still have to process the data in your program. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Config ConfigParser
On Wed, Mar 6, 2013 at 3:54 PM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: On Wed, 06 Mar 2013 15:19:53 +1100, Chris Angelico wrote: On Wed, Mar 6, 2013 at 3:07 PM, Chuck galois...@gmail.com wrote: I guess my question was more what is a config.file why/how do I use one. Thanks In its simplest form, a config file is one way to change a program's behaviour without editing the code. I don't think that's quite right, because your code has to be changed to read the data from the configuration file in the first place. It doesn't just happen by magic. Sure, but once you've made your code read from the config file, you can then edit the file only and it changes the program's actions. Of course, that's an *incredibly* broad description; amongst its coverage are such diverse elements as Apache reading an HTML file to serve, CPython reading a .py file, and the ROM BIOS reading a boot sector and jumping to it... but based on the OP's question I couldn't really be any more specific. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
