Manually add parameters in perl cgi - perl

Question

I've written a cgi script and it does the following:
#!/usr/bin/perl
use strict;
use warnings;
use CGI qw(:cgi-lib :standard);
use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
my $q = new CGI;
print $q->header;
print "<center>";
print $q->h1('Let\'s do something!');
print "</center>";
print $q->start_html(-title => 'Do something');
print $q->end_form;
our %in;
&ReadParse(%in);
my #keys = keys %in;
my #values = values %in;
main();
sub main{
print "<center>";
my $q0 = new CGI;
print $q0->start_form(
-name => 'sniff_button',
-method => 'POST',
-enctype => &CGI::URL_ENCODED,
);
print $q0->submit(
-name => 'button',
-value => 'Do something',
);
print $q0->end_form;
print "</center>";
}
What I want to do is add some parameters manually, because the next that depends on the previous state and not only on the current state (So I have to pass a parameter twice.).
I've done stuff with param() and URI, but none of them work. Any advice?

Answer 1

A hidden field is the answer:
sub main{
print "<center>";
my $q0 = new CGI;
print $q0->start_form(
-name => 'sniff_button',
-method => 'POST',
-enctype => &CGI::URL_ENCODED,
);
print $q0->hidden(
-name => 'machine_state',
-default => 'some_previous_value');
print $q0->submit(
-name => 'button',
-value => 'Do something',
);
print $q0->end_form;
print "</center>";
}