[Python-ideas] find-like functionality in pathlib

[Chris Barker]

On Tue, Dec 22, 2015 at 4:23 PM, Guido van Rossum <guido at python.org> wrote:

> The two-level iteration forced upon you by os.walk() is indeed often
> unnecessary -- but handling dirs and files separately usually makes sense,
>

indeed, but not always, so a simple API that allows you to get a flat walk
would be nice....

Of course for that basic use case, you could just write your own wrapper
>> around os.walk:
>>
>
sure, but having to write "little" wrappers for common needs is
unfortunate...

The problem isn't designing a nice walk API; it's integrating it with
>> pathlib.*
>
>
indeed -- I'd really like to see a *walk in pathlib itself. I've been
trying to use pathlib whenever I need, well, a path, but then I find I
almost immediately need to step out and use an os.path function, and have
to string-fy it anyway -- makes me wonder what the point is..

 And honestly, if open, os.walk, etc. aren't going to work with Path
>> objects,
>
>
but they should -- of course they should.....

Truly pushing for adoption of a new abstraction like this takes many years
> -- pathlib was new (and provisional) in 3.4 so it really hasn't been long
> enough to give up on it. The OP hasn't!
>

it will take many years for sure -- but the standard library cold at least
adopt it as much as possible.

Path.walk would be a nice start :-)

My example: one of our sysadmins wanted a little script to go thorugh an
entire drive (Windows), and check if any paths were longer than 256
characters (Windows, remember..)

I came up with this:

def get_all_paths(start_dir='/'):
    for dirpath, dirnames, filenames in os.walk(start_dir):
        for filename in filenames:
            yield os.path.join(dirpath, filename)

too_long = []
for p in get_all_paths('/'):
    print("checking:", p)
    if len(p) > 255:
        too_long.append(p)
        print("Path too long!")

way too wordy!

I started with pathlib, but that just made it worse.

now that I think about it, maybe I could have simpily used
pathlib.Path.rglob....

However, when I try that, I get a permission error:

/Users/chris.barker/miniconda2/envs/py3/lib/python3.5/pathlib.py in
wrapped(pathobj, *args)

    369         @functools.wraps(strfunc)
    370         def wrapped(pathobj, *args):
--> 371             return strfunc(str(pathobj), *args)
    372         return staticmethod(wrapped)
    373

PermissionError: [Errno 13] Permission denied:
'/Users/.chris.barker.xahome/caches/opendirectory'

as the error comes insider the rglob() generator, I'm not sure how to tell
it to ignore and move on....

os.walk is somehow able to deal with this.

-CHB

-- 

Christopher Barker, Ph.D.
Oceanographer

Emergency Response Division
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