Importing a .pl file - perl

Question

I was wondering how to import a Perl file to a script. I experimented with use, require and do, but nothing seems to work for me. This is how I did it with require:
#!/usr/bin/perl
require {
(equations)
}
print "$x1\n";
Is it possible to code for substituting a value (I get in my script) into equations.pl, then have my script use an equation defined in equations.pl to calculate another value? How do I do this?

Answer 1

You can require a .pl file, which will then execute the code in it, but in order to access variables, you need a package, and either "use" instead of require (the easy way) or via Exporter.
http://perldoc.perl.org/perlmod.html
Simple example: here's the stuff you want to import, name it Example.pm:
package Example;
our $X = 666;
1; # packages need to return true.
And here's how to use it:
#!/usr/bin/perl -w
use strict;
use Example;
print $Example::X;
This presumes Example.pm is in the same directory, or the top level of an #INC directory.

Answer 2

equations.pm file:
package equations;
sub add_numbers {
my #num = #_;
my $total = 0;
$total += $_ for #num;
$total;
}
1;
test.pl file:
#!/usr/bin/perl -w
use strict;
use equations;
print equations::add_numbers(1, 2), "\n";
output:
3

Answer 3

You can't import a file. You can execute a file and import symbols (variables and subs) from it. See Perl Modules in perlmod.

Answer 4

You've given very few details about equations.pl, but if the input can be given via a command line argument, then you can open a pipe:
use strict;
use warnings;
my $variable; #the variable that you will get from equations.pl
my $input=5; #the input into equations.pl
open (my $fh,"-|","perl equations.pl $input") or die $!;
while(my $output=<$fh>)
{
chomp($output); #remove trailing newline
$variable=$output;
}
if(defined($variable))
{
print "It worked! \$variable=$variable\n";
}
else
{
print "Nope, \$variable is still undefined...\n";
}
If this is the body of equations.pl:
use strict;
use warnings;
my $foo=$ARGV[0];
$foo++;
print "$foo\n";
Then the code above outputs:
It worked! $variable=6