use strict;
use warnings;

my $foo='$ans='; 
my $var=\$foo; 
my $transf='5;' ;
my $r5='$ans="hithere";'; 
my $var5=\$r5; 

testit("$$var$transf"); 
testit("${$var}$transf"); 
testit($$var.$transf); 
testit('$$var'.$transf); 

sub testit {
  my $ans;  
  my $string=shift; 
  $ans='???'; 
  my $eret=eval $string; 
  printf 'String:%-20s',$string;
  printf ' $ans:%-10s',$ans;
  printf ' $eret:%-10s',$eret;
  print "\n"; 
  }  # testit  


##</code><code>##

String:$ans=5;              $ans:5          $eret:5
String:$ans=5;              $ans:5          $eret:5
String:$ans=5;              $ans:5          $eret:5
String:$$var5;              $ans:???        $eret:$ans="hithere";