my $string = 'foo: $foo and bar: $bar\n';
print $string, "\n";

my $foo = "foozleberry pie";
my $bar = "barzleberry foo";

print eval 'qq(' . $string . ')';

##</code><code>##

my %vars = (
    foo => 'foozleberry pie',
    bar => 'barzleberry foo', 
); 
my $string = 'foo: $foo and bar: $bar'; 
$string =~ s/\$(\w+)/$vars{$1}/g; 
print $string, "\n";