First off, there is a difference between a package variable and a global variable. A package variable is accessible from outside the package, you just have to completely qualify the variable name. A global variable just means a variable visible everywhere within the current scope ... which means a variable declared at the start of a file (or package) is visible throughout that file.

Here's an example:

#!/usr/bin/env perl
use 5.010_000;
use strict;
use warnings;

{   package MyTest;
    my  $global  = 'global variable';
    our $package = 'package variable';
    sub access_global { return $global }
    1;
}

{   package main;
    my $package_var = $MyTest::package;
    my $global_var  = MyTest::access_global();
    my $warning_var = eval { $MyTest::global };
    say ">$_<" for $package_var, $global_var, $warning_var;
}

__END__
>package variable<
>global variable<
><
Name "MyTest::global" used only once: possible typo at /Users/io1/Work
+space/example/package_variables.pl line 16.
Use of uninitialized value $_ in concatenation (.) or string at /Users
+/io1/Workspace/example/package_variables.pl line 18.
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To get at a variable that is global within a package "MyTest" from outside "MyTest" you have to use a subroutine access_global()

As for the rest of your example, I suggest you use Class::Std to implement your inside-out class. There is a BUILD() method that you can use to initialize variables in non-standard ways.

Hope that helps =)