05/11/2010 09:07 PM, Terry Reedy wrote:
PS: I never understood why os.walk does not support hooks for key
events during such a tree traversal.
Either 1) it is intentionally simple, with the expectation that people
would write there own code for more complicated uses or 2) no one has
submitted a 'full-featured' version or 3) both.
If os.walk were rewritten, it should be as an iterator (generator).
Directory entry and exit functions could still be added as params.
It *is* an iterator/generator. However, I suspect you mean that
it should slurp the dirs/files iteratively instead of using
listdir() as was discussed on c.l.p a few months back.
The patch to os.py would be fairly simple, something like
--------------------------------------------
--- /usr/lib/python2.5/os.py
+++ ~/tmp/os.py
@@ -220,7 +220,7 @@
__all__.extend(["makedirs", "removedirs", "renames"])
-def walk(top, topdown=True, onerror=None):
+def walk(top, topdown=True, onerror=None, pre=None, post=None):
"""Directory tree generator.
For each directory in the directory tree rooted at top
(including top
@@ -296,15 +296,19 @@
else:
nondirs.append(name)
+ if pre is not None:
+ top, dirs, nondirs = pre(top, dirs, nondirs)
if topdown:
yield top, dirs, nondirs
for name in dirs:
path = join(top, name)
if not islink(path):
- for x in walk(path, topdown, onerror):
+ for x in walk(path, topdown, onerror, pre=pre,
post=post):
yield x
if not topdown:
yield top, dirs, nondirs
+ if post is not None:
+ post(top, dirs, nondirs)
--------------------------------------------
which would allow you to do things like
def pre(top, dirs, nondirs):
dirs = [d for d in dirs
if d not in ('RCS', '.svn', '.hg', '.git')]
return top, dirs, nondirs
def post(top, dirs, nondirs):
complex_process(top)
for top, dirs, nondirs in my.walk(PATH, pre=pre, post=post):
do_stuff(...)
I suspect if I thought about it much longer, only one would
really be needed, the other accommodated by the "topdown" parameter.
-tkc
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