Update: solved! Well, it will be solved...

I was playing around with tie and interpolation (for obfu purposes, FWIM), and I got what seems to me as a strange result:

#!/usr/bin/perl -l

use strict;
use warnings;

sub TIESCALAR { bless \my $i, shift }
sub FETCH { ${shift,}++ }

tie my $s, 'main';
print "$s$s$s";
print "$s$s$s";

tie my $t, 'main';
print " $t$t$t";
print " $t$t$t";

__END__
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This gives me the following output:

112
445
 012
 345
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Remark: please note that this is not an artifact of the minimalistic nature of the example, i.e. of the fact that I use main as the class providing the implementation of the variable, and that I do not provide a STORE method. I tried with more complex stuff and indeed the behaviour shown above persists.

Also note that with arrays everything works as one would naively expect - consider:

#!/usr/bin/perl -l

use strict;
use warnings;

sub TIEARRAY { bless \my $i, shift }
sub FETCHSIZE { 3 }
sub FETCH { ${shift,}++ }

tie my @s, 'main';
print "@s - @s - @s";

__END__
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0 1 2 - 3 4 5 - 6 7 8
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