friday:~ $ perl -mre=debug
$re = '$bar';
print map ">$_\n", grep /$re/, qw( $foo $bar );
compiling RE `$bar'
size 5 first at 1
   1: EOL(2)
   2: EXACT <bar>(5)
   5: END(0)
anchored `bar' at 0 (checking anchored) minlen 3 
Matching `$bar' against `bar'
  Setting an EVAL scope, savestack=12
   1 <$> <bar>            |  1:  EOL


friday:~ $ perl -mre=debug
$re = '\$bar';
print map ">$_\n", grep /$re/, qw( $foo $bar );
compiling RE `\$bar'
size 4 first at 1
   1: EXACT <$bar>(4)
   4: END(0)
anchored `$bar' at 0 (checking anchored isall) minlen 4 
>$bar