李伟 <liweifrie...@gmail.com> wrote on 06/09/2010 02:51:00 AM:
> Hi:
>
> I've written a x-10 problem as follows:
>
> public class Fun2
> {
> public static def main(argv:Rail[String]!) =
> {
> val a : DistArray[Int]
> =
> DistArray.make[Int](Dist.makeBlock(1..35),((i):Point)=>i*i);
> x10.io.Console.OUT.println(str(a));
> }
>
> static def str[T](a:DistArray[T]):String {
> var s : String = "";
> var first : Boolean = true;
> for(point in a)
> {
> if (first) first = false;
> else s += ",";
> s += a(point).toString();
> }
> return s;
> }
> }
>
> It can be compiled. And when running, the program crashed. The output
info
> is as follows:
>
> x10.lang.BadPlaceException: point (10) not defined at (Place 0)
> at x10.array.DistArray$2.apply(DistArray.java:613)
> at x10.array.DistArray$2.apply(DistArray.java:1)
> at x10.array.BaseRegion.check(BaseRegion.java:120)
> at x10.array.DistArray.checkPlace(DistArray.java:1407)
> at x10.array.DistArray.apply(DistArray.java:998)
> at Fun2.str(Fun2.java:149)
> at Fun2.main(Fun2.java:106)
> at Fun2$Main$2.apply(Fun2.java:51)
> at x10.lang.Runtime$5.apply(Runtime.java:4454)
> at x10.lang.Activity.run(Activity.java:217)
> at x10.lang.Runtime$Worker$3.apply(Runtime.java:3455)
> at x10.runtime.impl.java.Runtime.runAt(Runtime.java:105)
> at x10.lang.Runtime$Worker.loop(Runtime.java:3422)
> at x10.lang.Runtime$Worker.apply(Runtime.java:3308)
> at x10.lang.Runtime$Pool.apply(Runtime.java:3842)
> at x10.lang.Runtime.start(Runtime.java:4461)
> at Fun2$Main.main(Fun2.java:34)
> at x10.runtime.impl.java.Runtime.run(Runtime.java:50)
> at java.lang.Thread.run(Unknown Source)
>
> When changing the sentence:
> s += a(point).toString();
> into the new form:
> s += at(a.dist(point)){a(point).toString()};
> it runs well.
>
> In my opinion, toString is global. And therefore I don't need to use the
> "at" clause. Are there any problems here?
>
> Best regards,
> Wei Li
Hi, Wei,
Indeed, toString() is global, but array access is not. You are
getting the BadPlaceException from accessing a(point) in the wrong
place.
FYI,
s += (at(a.dist(point)) a(point)).toString();
should work (note that toString() is invoked in the place running
the loop -- only the array access has been executed remotely).
Hope this clarifies things,
Igor
P.S. It would be great if you stated your affiliation in your messages
when posting from a generic address (e.g., GMail).
--
Igor Peshansky (note the spelling change!)
IBM T.J. Watson Research Center
X10: Parallel Productivity and Performance (http://x10-lang.org/)
XJ: No More Pain for XML's Gain (http://www.research.ibm.com/xj/)
"I hear and I forget. I see and I remember. I do and I understand" --
Confucius
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