[Tutor] Python suddenly finding ".DS_Store" files in folder [use helper functions]

[Danny Yoo]

On Thu, 8 Apr 2004, Scot W. Stevenson wrote:

> > Actually, it _is_ Mac OS X running around inserting files.
>
> Ye Gods. How strange. They certainly don't tell you that in the switcher
> ads, do they ...

Hi Scot,


The page:

    http://www.bresink.de/osx/TinkerToolFAQ.html

is one place that talks about them in a little more detail.  Actually,
there appears to be a lot of controversy about the implementation of the
'.DS_Store' mechanism in the Finder; I googled for it, and the first thing
that comes up is a program to remove '.DS_Store' files.  *grin*



> > And if we want our programs to follow the same conventions, we'll have
> > to filter out those filenames ourselves.  If you write a small helper
> > function that filters out os.listdir()'s output, that should do the
> > trick.
>
> Yeah, now I have an ugly hack that checks if the file is .DS_Store and
> if so, skips it.



It shouldn't have to be ugly, if we add one level of indirection:

###
def mylistdir(directory):
    """A specialized version of os.listdir() that ignores files that
    start with a leading period."""
    filelist = os.listdir(directory)
    return [x for x in filelist
            if not (x.startswith('.'))]
###

We can use 'mylistdir()' function instead of os.listdir().  By writing a
helper function, we can limit the scope of the change to, effectively, a
few lines.



Hope this helps!