Proposal: Automatic Resource Management

[Joshua Bloch]

Neal,

>  I'd expect it to be something like
>
> try {
>    with (InputStream in : new FileInputStream(src))
>            with (OutputStream out : new FileOutputStream(dest)) {
>         byte[] buf = new byte[8 * 1024];
>        int n;
>        while ((n = in.read(buf)) >= 0)
>            out.write(buf, 0, n);
>    }
> } catch (IOException ex) {
>    showDialog("Copy failed.");
> }
>
> Looks about as nice,


No it doesn't.  Not even close. In java, the colon in this position would be
read by the typical programmer as "in"  (e.g., "for each String s in
stringList").  What we want (and what my proposal provides) is the equals
sign (=), which means assignment.  Also you have an extra level of nesting
for each variable. This is one of the things that we're trying to get away
from with this proposal.  A more honest indentation for your syntax would
be:

    try {
        with (InputStream in : new FileInputStream(src)) {
            with (OutputStream out : new FileOutputStream(dest)) {
                byte[] buf = new byte[8 * 1024];
                int n;
                while ((n = in.read(buf)) >= 0)
                    out.write(buf, 0, n);
            }
        }
    } catch (IOException ex) {
        showDialog("Copy failed.");
    }

That's three levels off indentation instead of one (more generallly, number
of resources + 1, instead of 1).

         Josh