Sharing variables between multiple submodules - perl

Question

I have a module foo that has extended sub-modules bar and baz. I want bar and baz to modify the same set of hashes that are in foo.
Right now I have something like:
my $foo = new foo;
my $bar = new foo::bar( $foo );
$bar->doStuff();
$bar->printSelf();
my $baz = new foo::bar( $foo );
$baz->doOtherStuff();
$baz->printSelf();
Inside one of the sub-modules the constructor looks like:
sub new {
my $class = shift;
my $self = shift;
--stuff--
bless $self, $class;
return $self;
}
Please don't laugh too hard. Is there a way I can do this without passing in $foo?
Thanks for reading. :)

Answer 1

I prefer to share things through methods. That way, no one has to know anything about the data structures or variables names (although you do need to know the method name):
{
package SomeParent;
my %hash1 = ();
my %hash2 = ();
sub get_hash1 { \%hash1 }
sub get_hash2 { \%hash2 }
sub set_hash1_value { ... }
sub set_hash1_value { ... }
}
Since SomeParent provides the interface to get at the private data structures, that's what you use in SomeChild:
{
package SomeChild;
use parent 'SomeParent';
sub some_method {
my $self = shift;
my $hash = $self->get_hash1;
...;
}
sub some_other_method {
my $self = shift;
$self->set_hash2_value( 'foo', 'bar' );
}
}

Answer 2

Your question is not very clear nor there is any code with hashes. But if you need module variables modified, you can use fully qualified name:
package Foo; # don't use lowercase named, they are reserved for pragmas
our %hash1 = ();
our %hash2 = ();
package Foo::Bar;
use Data::Dump qw(dd);
sub do_stuff {
$Foo::hash1{new_item} = 'thing';
}
sub do_other_stuff {
dd \%Foo::hash1;
}
package main;
Foo::Bar->do_stuff();
Foo::Bar->do_other_stuff();
But if you need to modify instance variables, you need to have reference to this instance. I see some strategies that would work:
inherit from Foo, so the hashes will be in instance of Foo::Bar
pass reference to Foo in constructor and store it as property in Foo::Bar
pass Foo reference as parameter to method
Proper solution depends on what you are trying to do and how you going to use it.