English Idiom in Unix: Directory Recursively

[Raymond Wiker]

Hans Georg Schaathun <hg at schaathun.net> writes:

> ["Followup-To:" header set to comp.lang.python.]
> On 18 May 2011 09:16:26 -0700, Thomas A. Russ
>   <tar at sevak.isi.edu> wrote:
> :  Well, unless you have a tree with backpointers, you have to keep the
> :  entire parent chain of nodes visited.  Otherwise, you won't be able to
> :  find the parent node when you need to backtrack.  A standard tree
> :  representation has only directional links.
>
> The array representation of a binary tree is standard, and the 
> «back» (parent) pointers are mathematically given.  /Some/ 
> standard tree representation do not have parent pointers.

	I don't think anybody mentioned *binary* trees. The context was
directory traversal, in which case you would have nodes with an
arbitrary (almost) number of children.

> You are right that I assumed parent pointers of some description;
> but it does demonstrate that tree walks can be done iteratively,
> without keeping a stack of any sort.

	Except that the chain of parent pointers *would* constitue a
stack.