Citeren Toralf Förster <toralf.foerster@[...].de> :

>  At Friday 04 July 2008 23:11:53 Bram via RT wrote :
> > According to our records, your request regarding
> >   "<variable> used only once: possible typo"
> > has been resolved.
> >
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> > this message.
> >
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> >
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> > <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=56530 >
> >
> 
>  Yes, "perl works as designed" might be an answer.
>  OTOH I'm wondering whether perl could be improved to not give a   
>  warning in such a case.
>  The term "used only once" is true for a line like "$foo = 1; " if   
>  ther's no further access to
>  the variable foo, but the given example shows that the variable is   
>  used after it is incremented...
> 

What really counts is how many times the variable is written, which is  
indeed not always the same as used.

In the case of your example: $counter is written only once in the  
script. The value is accessed and then incremented in a single  
operation.
This might be an error, this might not be an error.

What if your example was for example:

seq 1 7 | perl -we '$counter = 1; while (<STDIN> ) { print "line  
break\n" if ($couter++ % 3 == 0); print "line $counter = $_" }'


Personally, I don't really see a value (or a way) in imporoving it...


You don't want to see the warning?
Use a lexical variable.

You don't want to bother use a lexical variable?
Then disable warnings.


Warnings are about things that could be wrong.
If you write the name of a global variable only once in your script  
then that certainly could be wrong.


Kind regards,

Bram