Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #39955

Re: switch is shared declaration

Show all headers | View raw

"e.d.pro...@gmail.com" <e.d.programmer@gmail.com> writes:
>> > I don't use a lot of switches so I hadn't realized this but: 
>> > this is invalid: 
>> > if (1==1) { 
>> >  String s; 
>> > } else { 
>> >  s = "1"; 
>> > } 
>> > but this is fine: 
>> > switch (1) { 
>> >  case -1: 
>> >   String s; 
>> >   break; 
>> >  case 1: 
>> >   s = "1"; 
>> >   break; 
>> > }
>> The entire switch sort of has to be a single scope due to 
>> fall through (no break) being valid. 
>> Arne
> I guess it makes sense. You could call it a soft scope? In the if
> statement you get an undeclared variable error as it knows the if
> block will never execute with the else condition. In the switch
> statement it also will never execute both the declaration and the
> assignment, unless you remove the break. Since the break it optional,
> the compile sees it as one, though it also executes fine.

I wouldn't call it anything scope. Remember that you can create a lot of
mischief with labels and continue and breaks. And that needs to remain
compatible. And just because the compiler knows (can know) a block
cannot be reached, does not allow you to add illegal, but parseable
statements, e.g. "else { 0 = 1; }".

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

switch is shared declaration "e.d.pro...@gmail.com" <e.d.programmer@gmail.com> - 2023-05-24 05:15 -0700
  Re: switch is shared declaration Arne Vajhøj <arne@vajhoej.dk> - 2023-05-24 12:57 -0400
    Re: switch is shared declaration Arne Vajhøj <arne@vajhoej.dk> - 2023-05-24 13:16 -0400
    Re: switch is shared declaration "e.d.pro...@gmail.com" <e.d.programmer@gmail.com> - 2023-05-24 11:05 -0700
      Re: switch is shared declaration Michael Jung <miju@golem.phantasia.org> - 2023-05-28 12:57 +0200
  Re: switch is shared declaration Marcel Mueller <news.5.maazl@spamgourmet.org> - 2023-05-28 13:31 +0200
    Re: switch is shared declaration Eric Sosman <esosman@comcast-dot-net.invalid> - 2023-05-28 08:36 -0400
      Re: switch is shared declaration Marcel Mueller <news.5.maazl@spamgourmet.org> - 2023-05-28 15:16 +0200
        Re: switch is shared declaration Arne Vajhøj <arne@vajhoej.dk> - 2023-05-28 13:42 -0400
      Re: switch is shared declaration Arne Vajhøj <arne@vajhoej.dk> - 2023-05-28 13:43 -0400

csiph-web