Careful, B is an actual core module.

The OO competition for your subclass is a class which has-a instance of B and has-a instance of C as data members. It is fairly uncommon for multiple inheritance to make more sense than that kind of aggregation.

It may help decide if you reflect on whether A is-a B and A is-a C. Compare that to your answers to the same question with has-a substituted.

Because you justify the A class as a sort of opaque wrapper to keep users out of B and C, I suspect that aggregation will win. Your justification doesn't support a logical descent from B and C. An aggregate constructor based on your requirements will look something like this: 

# omit @ISA dance
sub new {
    my $class = shift;
    bless {
        Bobj => B->new(@_[0,1]),
        Cobj => C->new(@_[2,3])
    }, $class;
}

[download]
Again, don't really use 'B' as a package name, it's taken and will get very confusing.

After Compline,
Zaxo

In reply to Re: Understanding 'Multiple Inheritance' by Zaxo
in thread Understanding 'Multiple Inheritance' by punkish

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