Perl export to child modules - perl

Question

I have this parent module MyApp.pm:
package MyApp;
use Moose;
use base 'Exporter';
our #EXPORT = qw(msg);
sub msg {
print "Hello msg\n";
}
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which is inherited by this child module MyApp2.pm:
package MyApp2;
use Moose;
extends qw(MyApp);
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and when used in the App.cgi script like this:
#!/usr/bin/perl
use MyApp2;
msg();
I get error message:
Undefined subroutine &main::msg called at App.cgi line 3.
So the exported function does not work in the child class MyApp2 but works only if I use "use MyApp" instead of "use MyApp2". I assume the exported function should be accessible to the child modules also which is extending the parent class. What I am doing wrong.

Answer 1

Inheritance only changes how method calls are handled; function calls or variable accesses (like our #EXPORT) are not affected.
Instead of exporting a function, you could use it as a method:
use MyApp2;
MyApp2->msg;
but in this case, it would be cleaner to explicitly load MyApp in order to import the msg function, and to additionally load MyApp2 in order to load this class.
use MyApp;
use MyApp2;
msg;
It is generally advisable for a module to either be object oriented or to offer an interface via exported functions, but not do both.

Answer 2

Here is the solution I found for my request:
package MyApp;
use Moose;
use base 'Exporter';
our #EXPORT = qw(msg);
sub import {
my ($class, #args) = #_;
my $caller = $class.'::';
{
no strict 'refs';
#{$caller.'EXPORT'} = #EXPORT;
foreach my $sub (#EXPORT) {
next if (*{"$caller$sub"}{CODE});
*{"$caller$sub"} = \*{$sub};
}
}
goto &Exporter::import;
}
sub msg {
print "Hello msg MyApp\n";
}
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The idea here is I export all the contents of the "#EXPORT" array into the child module, only add none existent subs so will not overwrite any methods in the child class.
In this example above, this exports from MyApp to the child MyApp2.
This works for my own needs.