[FWP] How to do variable interpolation in a tr substitution string

[Mohan Chunkath <mchunkat@md2.vsnl.net.in>]

Dear Perl Gurus,
Why am I not able to do this as is in s/([a-z])/$h{$1}/g; etc?

The code I am trying to make work is:

srand;
    @new = ();
    @old = a .. z;
    while (@old) {
        push(@new, splice(@old, rand @old, 1));
    }
$"="";

$compstr=join("",@new);
#print $compstr;

while (<>)
{tr/a-z/$compstr/;print $_;
}

Thanks in advance. I am not sure whether it is OK to post this to this
Mailing List. My apologies if it is inappropriate. 
Mohan Chunkath

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