Well, this works too, if you really want to go through Exporter. I don't think you're going to be able to use as you would if the package were in a separate file since use really implies other fileness.

use strict;
use warnings;

use Test::More 'no_plan';

package my_temp_convert;

require Exporter;
our @ISA = ('Exporter');
our @EXPORT = qw(set_temp set_scale c f);

my $curr_scale=0; #centigrade, 1=faren
my $cur_ctemp=0;
sub set_scale{ $curr_scale=shift}
sub set_temp{  $cur_ctemp =shift}
sub c {return $cur_ctemp;}
sub f {return 32+(9*$cur_ctemp)/5}

package main;

Exporter::import( 'my_temp_convert' );

set_scale(1);
set_temp(0);

is( f(), 32, 'f() returns 32' );
is( c(), 0, 'c() returns 0' );
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