postprocessing in os.walk

[Peter Otten]

kj wrote:

> In <mailman.1196.1255347115.2807.python-list at python.org> Dave Angel
> <davea at ieee.org> writes:
> 
>>kj wrote:
>>> Perl's directory tree traversal facility is provided by the function
>>> find of the File::Find module.  This function accepts an optional
>>> callback, called postprocess, that gets invoked "just before leaving
>>> the currently processed directory."  The documentation goes on to
>>> say "This hook is handy for summarizing a directory, such as
>>> calculating its disk usage", which is exactly what I use it for in
>>> a maintenance script.
>>>
>>> This maintenance script is getting long in the tooth, and I've been
>>> meaning to add a few enhancements to it for a while, so I thought
>>> that in the process I'd port it to Python, using the os.walk
>>> function, but I see that os.walk does not have anything like this
>>> File::Find::find's postprocess hook.  Is there a good way to simulate
>>> it (without having to roll my own File::Find::find in Python)?
>>>
>>> TIA!
>>>
>>> kynn
>>>
>>>   
>>Why would you need a special hook when the os.walk() generator yields
>>exactly once per directory?  So whatever work you do on the list of
>>files you get, you can then put the summary logic immediately after.
> 
>>Or if you really feel you need a special hook, then write a wrapper for
>>os.walk(), which takes a hook function as a parameter, and after
>>yielding each file in a directory, calls the hook.  Looks like about 5
>>lines.
> 
> I think you're missing the point.  The hook in question has to be
> called *immediately after* all the subtrees that are rooted in
> subdirectories contained in the current directory have been visited
> by os.walk.
> 
> I'd love to see your "5 lines" for *that*.

import os

def find(root, process):
    for pdf in os.walk(root, topdown=False):
            process(*pdf)

def process(path, dirs, files):
    print path

find(".", process)

Peter