[Tutor] Excluding branches while walking directory tree

[Dave Kuhlman]

On Wed, Sep 13, 2006 at 11:15:44AM -0400, William O'Higgins Witteman wrote:
> Hello all,
> 
> I am looking for an approach for the following problem:
> 
> I have to walk a directory tree and examine files within it.  I have a
> set of directory names and filename patterns that I must skip while
> doing this walk.  How do I create a set of rules to skip files or
> directory branches?  I'm looking for something reasonably scalable, 
> 'cause I'm sure to need to update these rules in the future.
> 

For the first part of your problem, take a look at os.walk():
    http://docs.python.org/lib/os-file-dir.html
And also glob.glob():
    http://docs.python.org/lib/module-glob.html

The "in" operator is likely to be helpful in determining which
files to skip.  Suppose that you have a list of file names to be
ignored:

    skips = ['ignore1.txt', 'ignore2.txt']

then check a filename against the names to be skipped:

    if filename not in skips:
        # process the files not to be ignored here.

And, for more complex cases, you may want to write a test function
that returns True or False depending on whether the file is to be
ignored.  A trivial example:

    def good_file(filename, skips):
        if filename in skips:
            return False
        else:
            return True

    skips = ['ignore1.txt', 'ignore2.txt']
    if good_file(filename, skips):
        # process good files here
        o
        o
        o


Dave


-- 
Dave Kuhlman
http://www.rexx.com/~dkuhlman