As a self-taught Python user I am still looking for insight on the most pythonic and programmatically-friendly way of accomplishing a given task. In this case, I have written a script that will perform a “clean bzip2″ of a directory (or directories). Mac OS X (via AFP and netatalk, in my case) tends leaves a bunch of ugly files/directories hanging around and I would rather not include them in my compressed tar file.
In writing the script, though, I ran into some questions and I am not sure what the recommended approach would be. The script works, as it is, but I feel its a little hacked together and also a little limited in its application. There is something to be said for programs that "just work" (this does) but I want to take it a little further as an educational endeavor and would like it to appear robust, future-thinking, and pythonic. My initial questions are: 1. Is there a better way to implement a --quiet flag? 2. I am not very clear on the use of Exceptions (or even if I am using it in a good way here) — is what I have done the right approach? 3. Finally, in general: any feedback on how to improve this? (I am thinking, just now, that the script is only suitable for a command line usage, and couldn’t be imported by another script, for example.) Any feedback is greatly appreciated. Writing a script like this is a good learning tool (for me, at least). I have posted this email online if you want to see the script with pretty code formatting: http://blog.damontimm.com/python-script-clean-bzip/ Thanks for any insight you may provide. Damon Script follows ************************ #! /usr/bin/env python '''Script to perform a "clean" bzip2 on a directory (or directories). Removes extraneous files that are created by Apple/AFP/netatalk before compressing. ''' import os import tarfile from optparse import OptionParser IGNORE_DIRS = ( '.AppleDouble', ) IGNORE_FILES = ('.DS_Store', ) class DestinationTarFileExists(Exception): '''If the destination tar.bz2 file already exists.''' def ignore_walk(directory): '''Ignore defined files and directories when doing the walk.''' for dirpath, dirnames, filenames in os.walk(directory): dirnames[:] = [ dn for dn in dirnames if dn not in IGNORE_DIRS ] filenames[:] = [ fn for fn in filenames if fn not in IGNORE_FILES ] yield dirpath, dirnames, filenames def tar_bzip2_directories(directories): for directory in directories: file_name = '-'.join(directory.split(' ')) tar_name = file_name.replace('/','').lower() + ".tar.bz2" if os.path.exists(tar_name): raise DestinationTarFileExists() if not options.quiet: print 'Compressing files into: ' + tar_name tar = tarfile.open(tar_name, 'w:bz2') for dirpath, dirnames, filenames in ignore_walk(directory): for file in filenames: if not options.quiet: print os.path.join(dirpath, file) tar.add(os.path.join(dirpath, file)) tar.close() if __name__ == "__main__": parser = OptionParser(usage="%prog [options: -q ] [directory]") parser.add_option("-q", "--quiet", action="store_true", dest="quiet") options, args = parser.parse_args() directories = [] for arg in args: if os.path.isdir(arg): directories.append(arg) else: print "Ingoring: %s (it's not a directory)." % arg try: tar_bzip2_directories(directories) except DestinationTarFileExists: print "A tar file already exists this this directory name." print "Move or rename it and try again." _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
