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Re: I don't why I get 'not a statement' error in the following code...

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Date	Wed, 05 Oct 2011 10:21:40 -0700
From	Patricia Shanahan <pats@acm.org>
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Subject	Re: I don't why I get 'not a statement' error in the following code...
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On 10/5/2011 8:13 AM, Chad wrote:
> On Oct 4, 10:16 pm, Patricia Shanahan<p...@acm.org>  wrote:
>> On 10/4/2011 2:55 PM, Chad wrote:
>>
>>
>>
>>
>>
>>> On Oct 4, 11:33 am, Patricia Shanahan<p...@acm.org>    wrote:
>>>> On 10/4/2011 11:16 AM, Chad wrote:
>>>> ...
>>
>>>>> I don't get why 'Test.x;'  in main() isn't a variable. The expression
>>>>> 'Test.x' ends with a semicolon. So I just assumed it was a valid
>>>>> statement. However, the java compiler tells me something different.
>>>>> Ideas? Possible hints?
>>
>>>> See the JLS,http://java.sun.com/docs/books/jls/third_edition/html/statements.html...
>>
>>>> Only certain types of expressions can be turned into a statement by
>>>> adding a semicolon. They all have at least potential for side-effects at
>>>> the top level.
>>
>>>> May I ask why you need to execute Test.x without doing anything with the
>>>> result?
>>
>>> I still don't see why this expression can't be turned into a
>>> statement.
>>
>> Primarily, it is a matter of language definition, which is why I
>> included a link to the Java Language Specification.
>>
>> Are you saying that you think it is valid according to the JLS, or are
>> you saying that you do not understand why the Java designers decided not
>> to permit it?
>>
>
> I guess I don't understand why the Java designers decided not to
> permit it.

I think to reduce source code that is pure decoration, with no
effect on the program as run.

A Java implementation is allowed to optimize, as long as it keeps both
any results that are used and any side effects. Evaluating Test.x has no
side effects, and the result is dead, so the entire statement would be
dead code which the implementation can, and ideally should, firmly ignore.

Patricia

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I don't why I get 'not a statement' error in the following code... Chad <cdalten@gmail.com> - 2011-10-04 11:16 -0700
  Re: I don't why I get 'not a statement' error in the following code... Patricia Shanahan <pats@acm.org> - 2011-10-04 11:33 -0700
    Re: I don't why I get 'not a statement' error in the following code... Chad <cdalten@gmail.com> - 2011-10-04 11:43 -0700
      Re: I don't why I get 'not a statement' error in the following code... markspace <-@.> - 2011-10-04 12:14 -0700
      Re: I don't why I get 'not a statement' error in the following code... Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-10-04 12:20 -0700
    Re: I don't why I get 'not a statement' error in the following code... Chad <cdalten@gmail.com> - 2011-10-04 14:55 -0700
      Re: I don't why I get 'not a statement' error in the following code... Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-10-04 15:09 -0700
        Re: I don't why I get 'not a statement' error in the following code... Chad <cdalten@gmail.com> - 2011-10-04 15:11 -0700
          Re: I don't why I get 'not a statement' error in the following code... Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-10-04 17:30 -0700
      Re: I don't why I get 'not a statement' error in the following code... Stanimir Stamenkov <s7an10@netscape.net> - 2011-10-05 01:19 +0300
      Re: I don't why I get 'not a statement' error in the following code... Patricia Shanahan <pats@acm.org> - 2011-10-04 22:16 -0700
        Re: I don't why I get 'not a statement' error in the following code... Chad <cdalten@gmail.com> - 2011-10-05 08:13 -0700
          Re: I don't why I get 'not a statement' error in the following code... Patricia Shanahan <pats@acm.org> - 2011-10-05 10:21 -0700
          Re: I don't why I get 'not a statement' error in the following code... Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-10-05 20:43 -0400
            Re: I don't why I get 'not a statement' error in the following code... markspace <-@.> - 2011-10-05 19:36 -0700
              Re: I don't why I get 'not a statement' error in the following code... Lew <lewbloch@gmail.com> - 2011-10-05 19:43 -0700
  Re: I don't why I get 'not a statement' error in the following code... Roedy Green <see_website@mindprod.com.invalid> - 2011-10-05 12:00 -0700

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