[Pythonmac-SIG] islink() in macpath and directory walk

[Adam Eijdenberg]

> Maybe this is just a function that hasn't been used by others and has 
> thus
> never been updated...is there any reason not to have the function do the
> following return?
>
>   return macfs.ResolveAliasFile(s)[2]

Can't answer that one for you, but...

> 2) If I *do* want to follow aliases, I don't want to get trapped in an
> infinite loop caused when two folders contain aliases of each other.  Is
> there a clever "loop detection" algorithm for this short of keeping 
> track
> of every folder visited?  what is this condition called?  (I checked 
> ASPN
> with "loop detection", "walk detection", etc...without a lot of 
> success.)

This is more of a general programming question. One method I have used 
for similar projects, is start with two empty lists, say TO_PROCESS and 
DONE.

Add your first job (or in this case "root" folder) to TO_PROCESS and to 
DONE and then run something like the following:

while len (TO_PROCESS) > 0:
     job = TO_PROCESS.pop ()

     ... process job, possibly getting new child jobs and adding them as 
below ....

     if not (newChildJob in DONE):
         TO_PROCESS.append (newChildJob)
         DONE.append (newChildJob)

Not sure what you would exactly call this condition, but solving it with 
queues is usually fairly simple.

Hope that helps,
Adam