[Tutor] Problem with os.walk

[Tim Peters]

[Isr Gish]
> The docs say that you can del the dirnames list.

"the caller can modify the dirnames list in-place (e.g., via del or slice
assignment)"

"in-place" means things of the form

    del dirnames[1:]

or

    dirnames[:] = ['new directory']

> But when I tried doing it, it didn't work.

You have to show the exact code you used, else nobody can guess.

...

> I tried del

That's not enough to guess.  Maybe you did

    del dirnames

?  That indeed would not work.

> and dirnames = dirnames[0:0]

The binds dirnames to a brand new object, so is not an in-place modification
either.  If you want to empty dirnames entirely, two ways to do it in-place
are

    del dirnames[:]

or

    dirnames[:] = []

> Both didn't work. The only thing that wOrked was.
> for d in dirnames[:]:
>     dirnames.remove(d)

The two above will also work.

> And if I didn't make a copy it didn't work correctly. (it seems
> that for i in list works with indexing behindethe seigns).

Yes.  This is documented in the Language Reference manual (not the Library
Reference manual), in the section on "for" loops.