help needed on generator

[Mike C. Fletcher]

First, the generator problem:

	You are ignoring the results of the recursive calls to dirtree (which is 
a generator that yeilds at most one result at the moment).  You want to 
yeild the result of the dirtree, but that's supposed to be a generator, 
so you actually want to do:

for result in dirtree( os.path.join(root, dirname), predicate):
	yield result

Second the library-function problem:

	os.path.isdir() requires a fully-specified path or one relative to the 
current working directory.

HTH,
Mike

8<____________ walk.py ___________
#Import generators.
from __future__ import generators

#Import modules.
import os, sys

def true(*args, **kwargs):
     """The identically true function."""
     return 1

def dirtree(root, predicate = true):
     """Visit a directory tree, using a generator.

     A predicate can be provided to trim the directories visited."""

     #Yield root dir.
     if predicate(root):
         yield root

     #Recurse into subdirectories.
     directories = [
         dir for dir in os.listdir(root)
         if os.path.isdir(os.path.join(root,dir))
     ]
     for dirname in directories:
         if predicate(dirname):
             for result in dirtree(os.path.join(root, dirname), predicate):
                 yield result


if __name__ == '__main__':
     try:
         root = sys.argv[1]
     except IndexError:
         root = os.getcwd()

     for dir in dirtree(root):
         print dir


Gonçalo Rodrigues wrote:
> Hi,
> 
> I've coded this generator to traverse a directory tree. 
> 
> #Import generators.
> from __future__ import generators
> 
> #Import modules.
> import os, sys
> 
> def true(*args, **kwargs):
>     """The identically true function."""
>     return 1
> 
> def dirtree(root, predicate = true):
>     """Visit a directory tree, using a generator.
> 
>     A predicate can be provided to trim the directories visited."""
> 
>     #Yield root dir.
>     if predicate(root):
>         yield root
> 
>     #Recurse into subdirectories.
>     for dirname in [dir for dir in os.listdir(root) if
> os.path.isdir(dir)]:
>         if predicate(dirname):
>             dirtree(os.path.join(root, dirname), predicate)
> 
> 
> if __name__ == '__main__':
>     try:
>         root = sys.argv[1]
>     except IndexError:
>         root = os.getcwd()
> 
>     for dir in dirtree(root):
>         print dir
> 
> When I feed "C:" to the sucker (run as script) only "C:" gets printed.
> Can anyone point out to me what I am doing wrong?
> 
> P.S: I want to keep the order: first yield the directory then go and
> visit the childs.
> 
> Thanks in advance and best regards,
> Gonçalo Rodrigues


-- 
_______________________________________
   Mike C. Fletcher
   http://members.rogers.com/mcfletch/