macpath.py 文件源码

def walk(top, func, arg):
    """Directory tree walk with callback function.

    For each directory in the directory tree rooted at top (including top
    itself, but excluding '.' and '..'), call func(arg, dirname, fnames).
    dirname is the name of the directory, and fnames a list of the names of
    the files and subdirectories in dirname (excluding '.' and '..').  func
    may modify the fnames list in-place (e.g. via del or slice assignment),
    and walk will only recurse into the subdirectories whose names remain in
    fnames; this can be used to implement a filter, or to impose a specific
    order of visiting.  No semantics are defined for, or required of, arg,
    beyond that arg is always passed to func.  It can be used, e.g., to pass
    a filename pattern, or a mutable object designed to accumulate
    statistics.  Passing None for arg is common."""
    warnings.warnpy3k("In 3.x, os.path.walk is removed in favor of os.walk.",
                      stacklevel=2)
    try:
        names = os.listdir(top)
    except os.error:
        return
    func(arg, top, names)
    for name in names:
        name = join(top, name)
        if isdir(name) and not islink(name):
            walk(name, func, arg)