you will still get an error that you can't use 3 as a reference while strict is in effect. This is because Perl sees %${w} and interprets it as %{ ${ w }}, trying to interpret the value of $w as a reference.

Did you test your assumption? 

my $w = 5;
my $str = "abc";
my $line = sprintf "%${w}s ", $str;
print "'$line'\n";
__END__
'  abc '

[download]

The format string is %5s with perl 5, version 20, subversion 2 (v5.20.2).

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In reply to Re^2: use of strict by shmem
in thread use of strict by geofflh

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