I'd like all the classes in my large package to all have the same $VERSION (as defined in $My::Package::Version::VERSION). This is easy with Exporter and @EXPORT = qw($VERSION); all of my classes must then simply "use My::Package::Version".

But I wanted to make it a little easier by only having to add the "use" statement to the small handful of base classes (rather than the nearly hundred other classes that inherit from them). I tried to work up this idea: 

package My::Package::Version;
use strict;
use vars qw(@ISA $VERSION @EXPORT);

@ISA = qw(Exporter);
$VERSION = 3.14;
@EXPORT = qw($VERSION);

sub import {
    # try to handle multiple levels of inheritance:
    my $i = 0;
    my $pkg = caller($i);
    while ($pkg &&
           $pkg =~ m/^My::Package::/o &&
           !defined ${"$pkg::VERSION"}) {
        __PACKAGE__->export_to_level($i+1);
        $pkg = caller(++$i);
    }
}
1;

[download]
The problem, of course, is that this doesn't work; even though My::Package::A uses My::Package::B (and ISA ::B), which itself uses My::Package::Version, only $B::VERSION gets set, not $A::VERSION (since caller(2) becomes "main", not My::Package::A when A compiles B).

Is there some tricky solution to this?

Thanks,

-Aaron

In reply to variable "inheritance"; viral $VERSION by amackey

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