Your list of variables. Each variable on it's own line, like you did, IMHO make sense only when you documenting it,

# Variables
my $host;     # hostname to connect to
my $engine;   # can be 'foo' or 'bar'
my $user;     # username for authorization
my $password; # password for auth
my $port;     # tcp port to connect
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but if you have so many variables with self-explanatory names you can do this:

my ($host, $engine, $user, $password, $port);
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