Re: Associative arrays and memory

[Peter Stephenson <pws@xxxxxxxxxxxxxxxxx>]

"Bart Schaefer" wrote:
> Of course, a non-special associative array can contain special parameters.
> That was part of the idea of using a parameter hash as the implementation.
> And that would be the way to do it, rather than make the associative array
> itself special.

OK, I missed this point, then you're stuck with something of the
complexity of what you had if you want to restore it.  But what's
wrong with making the associative array special?  It could do some
sort of dispatch based on the values of the hash it stored.  Then you
could get away with doing only a shallow save of the assoc array at
this point (but see below), i.e. pretty much like what happens with
other special parameters.

Possibly in practice the parent AA will have to be marked as special,
even if its own functionality is as normal.  The alternatives to that
are (1) check all non-special AA's for special contents at the point
in question, which probably isn't on (2) the elements of the AA stop
being special, which is a bit counterintuitive.

> It doesn't matter that a whole array is being assigned to the hash, does
> it?  Even creating a scalar with the same parameter name would require
> that it be saved/restored.

That's true if the assoc array is not special, but its elements are.
If the AA is itself special, it retains that behaviour on set/restore.
Consider
   PATH=foo:bar builtin_or_func
--- here PATH still works the same way as always, just with special
save/restore.  Then assigning a scalar to zle would give some kind of
error.

> So the question is, should it ever be the case that
> 
>     zle=(? BUFFER "this is the command line" ... ?) builtin_or_func
> 
> causes the old command line to be restored following builtin_or_func?
> And if we save and restore such a hash by the simple stacking method, is
> $zle[BUFFER] going to give the right thing after builtin_or_func?

If the bits of the AA are special, and you want to restore them, then
as I said above it seems you'll need the full complexity of the
copyarams() mechanism because you can't guarantee restoring the state
otherwise.  Should it work?  Probably yes.  At some stage we will want
whole assoc array assignments like 'hash2=$hash1', which presumably
requires something like copyparams() anyway.  Maybe I'll just have to
bit the bullet and check for memory leaks properly :-(.

-- 
Peter Stephenson <pws@xxxxxxxxxxxxxxxxx>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56100 Pisa, Italy