Ugghhh! $++ doesn't do what you think. You think $| == 0 and that $|++ makes $|==1. Sure IFF $|==0. But what when some other fool does $|++. Then your $|++ doesn't do anything. Even worse $|-- doesns't set $|==0, because you blindly did $++. Now maybe your think this turns it into some sort of recursive lock type thing. No! because someone could have done $|=0 or $|=1 in another part or the code, cuz it's is the RightThing(tm).

Just remember that $|++ is a SIN. Don't do it.

BTW, what does $|==-1 even mean?

$| is magic. It is always either 0 or 1. $|++ sets its value to 1 no matter what its original value was.

However, $|-- is a bit trickier. $|-- toggles the value of $|. So, its actually a lot like $| = !$_

% perl -le 'print $| and $|++ for 1..5;'
0
1
1
1
1

% perl -le 'print $| and $|-- for 1..5;'
0
1
0
1
0
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-Blake

'perldoc perlvar'

The only values that count here are 0 and non-zero.

Consider the tao of $|--