Perl: Invoke variable using other variable

At my last post http://icfun.blogspot.com/2008/05/perl-call-function-using-variable.html I have mentioned how to invoke a Perl function using a variable. Today i'm going to tell how to invoke a variable using other variable. For example below example.

## Initially
$variable = "Before";
print "$variable\n";

## Take the variable name into another
$variable_name = "variable";
## Invoking the value using other variable
${$variable_name} = "Now";
print "$variable\n";

If you need to use array invoke using a variable, then below code example.

## Initially the array
@variable = qw( Before  After);
print "@variable\n";

## Take the array name into another variable
$variable_name = "variable";
## Invoking the array using other variable
@{$variable_name} = qw(All have changed);
print "@variable\n";

Infact you can use Hash also for this purpose. But remember as I told you that this example doesn't work when strict is used. May be there is a way for strict, but I don't know.