Generators and nested functions

[Peter Hansen]

"Edward C. Jones" wrote:
> 
> The following code would be a simple way for doing a useful thing except
> that it doesn't work. Why not? Any easy fixes?
> 
> from __future__ import generators
> import os
> 
> def walk_dirs(startdir):
>      def visit(arg, dirname, names):
>         yield dirname
> 
>      os.path.walk(startdir, visit, None)
> 
> if __name__ == '__main__':
>      for dir in walk_dirs('/some/small/directory'):
>         print dir

I don't know much about generators (haven't tried them
yet), but I believe that the method/function you want
turned into a generator *must* use the yield statement
somewhere.  Your walk_dirs() does not use yield, but
does define a method visit() which is itself a generator.