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Groups > comp.lang.java.programmer > #31146

Re: ensuring unreachability

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On 2/18/2015 9:40 AM, Jukka Lahtinen wrote:
> Eric Sosman <esosman@comcast-dot-net.invalid> writes:
>
>>      Remember, the underlying purpose is to guard against a
>> maintainer who might inadvertently introduce a fall-through.
>
> Why not just insert the break; for every case?
> That's what it is for.

     The original code was oddly structured:

	case E1:
	    if (...) {
	       ...; return;
	    } else if (...) {
	       ...; throw ...;
	    } else {
	       ...; continue;
	    }
	case E2:
	    ...

Inserting a `break' right before the E2 case would provoke a
compile-time error because the statement would be unreachable.

     Andreas worries that someone might add a new alternative
to the `if' ladder, one that doesn't `return' or `throw' or
otherwise exit the `switch', thereby producing an unwanted
fall-through into E2.  I think the most straightforward way to
accomplish this is to eliminate the final `else' and brackets,
putting the `...; continue;' at the "top level" of the case.

-- 
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM

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ensuring unreachability Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-02-17 09:54 +0000
  Re: ensuring unreachability Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-02-17 08:23 -0500
  Re: ensuring unreachability Leif Roar Moldskred <leifm@huldreskog.localdomain> - 2015-02-17 13:54 -0600
  Re: ensuring unreachability Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-02-17 15:51 -0500
    Re: ensuring unreachability Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-02-18 00:40 +0000
      Re: ensuring unreachability Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-02-18 08:49 -0500
        Re: ensuring unreachability Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2015-02-18 16:40 +0200
          Re: ensuring unreachability Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-02-18 10:16 -0500
            Re: ensuring unreachability Jerry Stuckle <jstucklex@attglobal.net> - 2015-02-18 11:02 -0500
              Re: ensuring unreachability Robbie Brown <rob@example.com> - 2015-02-19 09:48 +0000
                Re: ensuring unreachability Gene Wirchenko <genew@telus.net> - 2015-02-20 09:39 -0800
              Re: ensuring unreachability Robbie Brown <rob@example.com> - 2015-02-19 09:50 +0000
              Re: ensuring unreachability v_borchert@despammed.com (Volker Borchert) - 2015-02-19 18:20 +0000
                Re: ensuring unreachability Jerry Stuckle <jstucklex@attglobal.net> - 2015-02-19 15:24 -0500
        Re: ensuring unreachability Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-02-19 01:28 +0000
  Re: ensuring unreachability Arne Vajhøj <arne@vajhoej.dk> - 2015-02-17 18:49 -0500
  Re: ensuring unreachability Martin Gregorie <martin@address-in-sig.invalid> - 2015-02-18 00:59 +0000

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