The problem is that the line use XX::Blah; is instructing Perl to search for a file Blah.pm located in a subdirectory XX within one of the library subdirs described by %INC.

To use a package that is included in the current source file, you don't need to ask Perl to find it for you, it already knows where it is. So don't use it, just use it :).

#! perl -slw
use strict;

package XX::Blah;

sub new {
    return bless { proof=>'You got me!' } , shift;
}

sub proof {
    my $self = shift;

    print $self->{proof};
}

package main;

my $test = new XX::Blah;

$test->proof();

__END__
# Output
C:\test>216900
You got me!

C:\test>
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