Yes, you can scope to your hearts content with {} blocks. For those
not aware of this:
There's a rarely used feature of the java language: separate blocks.
You can put { (statements) } anywhere in java code where a statement
is legal. Like any other occurrence of {} to delimit code, any
variable declarations inside the {} are not visible outside the
brackets. So, this:
public void test() {
int foo = 1;
{
int bar = foo + 2;
}
//MARK
}
is legal, and 'bar' will not be visible at the mark. Because of this
feature, @Cleanup is what it is; if you want an explicit close point,
then use a block. In practice, a decent amount of resources you may
want to @Cleanup require try/catch blocks, which are of course also
their own scope:
try {
@Cleanup InputStream in = new FileInputStream(path);
} catch ( IOException e ) {
throw new DatabaseAccessException(e);
}
After all, the act of creating a resource tends to throw the same
kinds of exceptions as using the resource.
Funny thing, this @Cleanup thing. I never considered this style of ARM
until forced into it by lombok's particular limitations (Specifically:
it needs code that passes the tokenizer and tree maker before lombok
can run its transformations), and then it turns out it's in many ways
superior to the existing proposal. I don't think coin is going to go
this route though, it's a bit late for such a drastic change.
On Sep 1, 4:31 pm, Jess Holle <je...@ptc.com> wrote:
> I actually prefer @Cleanup to the JDK 7 proposal in that it presumably
> just cleans up at the end of the variable's scope ala C++.
>
> If you need ordering amongst several @Cleanup variables, then you can
> always introduce {...} scoping, right? If so, then I'd rather introduce
> such things only as needed rather than the JDK 7 proposal's approach.
>
>
>
> Roel Spilker wrote:
> > Casper,
>
> > You are correct. I just wanted the other readers to know that it is
> > not limited to "close". It is however limited to no-args methods.
>
> > Roel
>
> > On Sep 1, 4:10 pm, Casper Bang <casper.b...@gmail.com> wrote:
>
> >> I think you misunderstood Roel. I am aware of the method name argument
> >> override, I was merely exploring the different implementations and
> >> implications of these two ARM blocks. The JDK7 version would have to
> >> rely on a new interface Disposable being added to the libraries, as
> >> the abomination known as checked exceptions (IOException) once again
> >> gets in the way of simply using the existing Closable. Lombok couldn't
> >> care less what it's closing and could in fact be used as a C++
> >> deconstructor. Correct?
>
> >> /Casper
>
> >> On 1 Sep., 15:47, Roel Spilker <r.spil...@gmail.com> wrote:
>
> >>> Caster, that is not entirely correct. The "close" methode (actually,
> >>> close is just the default, you can specify an other method name if you
> >>> want) will be called when the variable goes out of scope.
> >>> Unfortunately, java does not allow an annotation on a code block. So
> >>> an equivalent programm would be:
>
> >>> {
> >>> @Cleanup InputStream in = new FileInputStream(...);
> >>> // Do something else...
>
> >>> }
>
> >>> On Sep 1, 3:10 pm, Casper Bang <casper.b...@gmail.com> wrote:
>
> >>>> The neat thing about this is that we do not have to wait until the
> >>>> Java API has been retrofitted with the Disposable interface. However,
> >>>> you won't get the scope limitation benefits (the in and out variable
> >>>> is scoped the whole method). I kind of wish we could use annotations
> >>>> on blocks, so this would be possible instead:
>
> >>>> @Cleanup{
> >>>> InputStream in = new FileInputStream( ... );
> >>>> // Do something...
>
> >>>> }
>
> >>>> @Cleanup{
> >>>> InputStream in = new FileInputStream( ... );
> >>>> // Do something else...
>
> >>>> }
>
> >>>> /Casper
>
> >>>> On 1 Sep., 14:53, Roel Spilker <r.spil...@gmail.com> wrote:
>
> >>>>> For ARM-blocks you can have a look at the @Cleanup annotation of
> >>>>> Lombok and have ARM-blocks for Java right now!
>
> >>>>> The following code will close both streams correctly after they run
> >>>>> out of scope.
>
> >>>>> import lombok.Cleanup;
> >>>>> import java.io.*;
>
> >>>>> public class CleanupExample {
> >>>>> public static void main(String[] args) throws IOException {
> >>>>> @Cleanup InputStream in = new FileInputStream(args[0]);
> >>>>> @Cleanup OutputStream out = new
> >>>>> FileOutputStream(args[1]);
> >>>>> byte[] b = new byte[10000];
> >>>>> while (true) {
> >>>>> int r = in.read(b);
> >>>>> if (r == -1) break;
> >>>>> out.write(b, 0, r);
> >>>>> }
> >>>>> }
>
> >>>>> }
>
> >>>>> Seehttp://projectlombok.org/features/Cleanup.htmlformore
> >>>>> information
>
> >>>>> On Sep 1, 2:19 pm, "joel.neely" <joel.ne...@gmail.com> wrote:
>
> >>>>>> According to coverage
> >>>>>> athttp://arstechnica.com/apple/reviews/2009/08/mac-os-x-10-6.ars/10
> >>>>>> , Snow Leopard, the latest version of Mac OS X, added "blocks" to C.
> >>>>>> The article illustrates this new language construct with the by-now
> >>>>>> canonical ARM and home-grown-control-structure examples.
>
> >>>>>> Hey, Java! Closures to the left of me [JRuby, Scala, etc.], blocks to
> >>>>>> the right [C on OS X], here I am, stuck in the middle with you!
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