It's pretty much in the documentation for eval, but I try to explain a bit nonetheless.

There are two completely different usages of eval. The first:

eval {
    # code here that might throw exceptions
    # this is the form that you described
}
[download]

And the second:

my $string = '4 + 5';
my $answer = eval $string;
[download]

This second form is what you need. It takes a string, and compiles and runs it like a little Perl program.

There are other serialization formats that you might want to use instead of Data::Dumper like Storable, YAML, JSON and XML. They have the advantage that you don't have to eval your code, which is a security risk if you don't trust your data source.