How can I traverse a file system with a generator?

As of Python 3.4, you can use the glob() method from the built-in pathlib module:

import pathlib
p = pathlib.Path('.')
list(p.glob('**/*'))    # lists all files recursively

I agree with the os.walk solution

For pure pedantic purpose, try iterate over the generator object, instead of returning it directly:

def grab_files(directory):
    for name in os.listdir(directory):
        full_path = os.path.join(directory, name)
        if os.path.isdir(full_path):
            for entry in grab_files(full_path):
                yield entry
        elif os.path.isfile(full_path):
            yield full_path
        else:
            print('Unidentified name %s. It could be a symbolic link' % full_path)

Why reinvent the wheel when you can use os.walk

import os
for root, dirs, files in os.walk(path):
    for name in files:
        print os.path.join(root, name)

os.walk is a generator that yields the file names in a directory tree by walking the tree either top-down or bottom-up