[Swift-devel] variable cleanup

[Mihael Hategan]

There is code in trunk now to clean up variables when they go out of
scope. This applies to compound procedure scopes, iterate scopes,
foreach scopes and if/[then|else]. And this reminds me, the main/program
scope should also have this.

Cleanup means that:
- some of the in-memory data is nullified. I'm not sure this is
necessary since the data should be garbage collected by the java GC.
- some mappers (in particular ones advertising themselves as temporary -
e.g. concurrent) should remove the files that they created

Sadly this isn't fully what I wanted, for example:

file a[] <some proper mapper>;

foreach i in [1:1000000] {
  a[i] = generate(i);
}

In the above case it would be nice if no memory reference would be held
to the various a[i] after they are "assigned".