I suggest that unused labels should cause an error.
This prevents bugs due to typos of `default' label.

Robert (Japanese)

"Robert" <Robert_member@pathlink.com> wrote in message news:br1r2o$19i0$1@digitaldaemon.com...
> I suggest that unused labels should cause an error.
> This prevents bugs due to typos of `default' label.

I understand what you're saying. The problem with it, though, is that the label may be a target of a goto from inside a version statement elsewhere in the function. Wrapping the label in another version winds up looking kinda ugly.

The default typo bug is alleviated somewhat by the language inserting a default:assert(0); if no other default is supplied.

> > I suggest that unused labels should cause an error.
> > This prevents bugs due to typos of `default' label.
>
> I understand what you're saying. The problem with it, though, is that the label may be a target of a goto from inside a version statement elsewhere
in
> the function. Wrapping the label in another version winds up looking kinda ugly.
>
> The default typo bug is alleviated somewhat by the language inserting a default:assert(0); if no other default is supplied.

Absolutely not. Your ability to flabbergast me on this issue has just expanded its borders. If the typo issue isn't compelling evidence in favour of a mandatory default, I can't conceive of what will be.

Maybe I'll give up, and just program in C# ...

:(

"Matthew Wilson" <matthew.hat@stlsoft.dot.org> wrote in message news:br3klk$uuk$1@digitaldaemon.com...
> > > I suggest that unused labels should cause an error.
> > > This prevents bugs due to typos of `default' label.
> >
> > I understand what you're saying. The problem with it, though, is that
the
> > label may be a target of a goto from inside a version statement
elsewhere
> in
> > the function. Wrapping the label in another version winds up looking
kinda
> > ugly.
> >
> > The default typo bug is alleviated somewhat by the language inserting a default:assert(0); if no other default is supplied.
>
> Absolutely not. Your ability to flabbergast me on this issue has just expanded its borders. If the typo issue isn't compelling evidence in
favour
> of a mandatory default, I can't conceive of what will be.
>
> Maybe I'll give up, and just program in C# ...
>
> :(

FWIW, both C# and Java do the C-style implicit default:break;. The default is not mandatory. In neither C# nor Java (according to their specifications, I didn't try the compilers) are unreferenced labels an error. I'm not arguing that C# or Java did this right, I'm just pointing out that there doesn't seem to be any consistent view in the C-like-language programming community how switch and labels ought to work.

Hmm.  Though I think goto isn't a good example,
the problem may occur when labeled break is used.
I back it down.  ...since I've never done the typo, ...no,
I think now that this problem should be solved by other way
(e.g. improving switch statement syntax itself.)


In article <br417o$1iea$1@digitaldaemon.com>, Walter says...
>
>
>"Matthew Wilson" <matthew.hat@stlsoft.dot.org> wrote in message news:br3klk$uuk$1@digitaldaemon.com...
>> > > I suggest that unused labels should cause an error.
>> > > This prevents bugs due to typos of `default' label.
>> >
>> > I understand what you're saying. The problem with it, though, is that
>the
>> > label may be a target of a goto from inside a version statement
>elsewhere
>> in
>> > the function. Wrapping the label in another version winds up looking
>kinda
>> > ugly.
>> >
>> > The default typo bug is alleviated somewhat by the language inserting a default:assert(0); if no other default is supplied.
>>
>> Absolutely not. Your ability to flabbergast me on this issue has just expanded its borders. If the typo issue isn't compelling evidence in
>favour
>> of a mandatory default, I can't conceive of what will be.
>>
>> Maybe I'll give up, and just program in C# ...
>>
>> :(
>
>FWIW, both C# and Java do the C-style implicit default:break;. The default is not mandatory. In neither C# nor Java (according to their specifications, I didn't try the compilers) are unreferenced labels an error. I'm not arguing that C# or Java did this right, I'm just pointing out that there doesn't seem to be any consistent view in the C-like-language programming community how switch and labels ought to work.
>
>

Robert (Japanese)

Walter wrote:
> "Robert" <Robert_member@pathlink.com> wrote in message
> news:br1r2o$19i0$1@digitaldaemon.com...
> 
>>I suggest that unused labels should cause an error.
>>This prevents bugs due to typos of `default' label.
> 
> 
> I understand what you're saying. The problem with it, though, is that the
> label may be a target of a goto from inside a version statement elsewhere in
> the function. Wrapping the label in another version winds up looking kinda
> ugly.

I have myself coded the infamous "defualt:" goto-label, only to have my default case ignored.  Then, I spent a day looking at the code and not seeing the misspelling.

My own thought was to spell it "case default:" rather than just "default:" to make the difference more obvious.

Another solution to a mispelled default looking like a label is my idea for a new switch statement (as mentioned before) wherein the braces of a case are required...

switch expr
{
case x
{
}

// no code allowed here

default
{
}
}

not only does this form of switch/case _not_ have a colon (and therefore not
look like a label), but no code (and therefore no labels) are allowed within the
switch but outside a case.

And of course I don't want fall-through, but that's another matter.  :)

In article <br3gdl$pan$1@digitaldaemon.com>, Walter says...
>
>
>"Robert" <Robert_member@pathlink.com> wrote in message news:br1r2o$19i0$1@digitaldaemon.com...
>> I suggest that unused labels should cause an error.
>> This prevents bugs due to typos of `default' label.
>
>I understand what you're saying. The problem with it, though, is that the label may be a target of a goto from inside a version statement elsewhere in the function. Wrapping the label in another version winds up looking kinda ugly.
>
>The default typo bug is alleviated somewhat by the language inserting a default:assert(0); if no other default is supplied.
>
>

Richard Krehbiel wrote:

> Walter wrote:
> 
>> "Robert" <Robert_member@pathlink.com> wrote in message
>> news:br1r2o$19i0$1@digitaldaemon.com...
>>
>>> I suggest that unused labels should cause an error.
>>> This prevents bugs due to typos of `default' label.
>>
>>
>>
>> I understand what you're saying. The problem with it, though, is that the
>> label may be a target of a goto from inside a version statement elsewhere in
>> the function. Wrapping the label in another version winds up looking kinda
>> ugly.
> 
> 
> I have myself coded the infamous "defualt:" goto-label, only to have my default case ignored.  Then, I spent a day looking at the code and not seeing the misspelling.
For me, using an editor that does syntax highlighting can help avoid this kind of error.

YMMV.

(Of course, if I haven't made any stupid programming mistakes recently, it's because I haven't worked on any programs recently.)


Justin

> 
> My own thought was to spell it "case default:" rather than just "default:" to make the difference more obvious.
>