An alternative to having Slave.pm export the variable would be to write a get/set wrapper for $Slave::type:

package Slave;
my $type;
sub type(;$) { $type = shift if @_; $type }
1;

package main;
use strict;
use Slave;
Slave::type("FOO");
print Slave::type . "\n";
Slave::tpye("BAR"); # dies
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Or, if you're on Perl 5.6+ and don't care about supporting archaic versions of Perl (and you should rarely care about such things)...

package Slave;
my $type;
sub type(;$) :lvalue { $type = shift if @_; $type }
1;

package main;
use strict;
use Slave;
Slave::type = "FOO";
print Slave::type . "\n";
Slave::tpye = "BAR"; # dies
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