How to create a class that doesn't inherit from any other class?

Question

If you create a class:

class Foo { }

the class will inherit all of its methods from Any, and then Mu.

I want to create a class that doesn't inherit from any other class: it should contain a single FALLBACK method that should catch all method calls to instances of that object.

I've looked through the MetaModel code, but there does not seem to be a simple way to achieve this goal. All suggestions are welcome!

UPDATE: I decided to go the intercept any method call way as described by Jonathan Worthington. This resulted in two new Perl 6 modules on CPAN: InterceptAllMethods and Object::Trampoline.

Answer 1

Here is another idea: You could create a new meta class that inherits from ClassHOW, but overrides the methods that role Perl6::Metamodel::MROBasedMethodDispatch provides with versions that skip all parent classes.

For example, this:

# Maybe this belongs on a role. Also, may be worth memoizing.
method can($obj, $name) {
    my @meths;
    my %smt := self.submethod_table($obj);
    if nqp::existskey(%smt, $name) {
        @meths.push(%smt{$name});
    }
    for self.mro($obj) {
        my %mt := $_.HOW.method_table($_);
        if nqp::existskey(%mt, $name) {
            @meths.push(%mt{$name})
        }
    }
    @meths
}

would become

method can($obj, $name) {
    my @meths;
    my %smt := self.submethod_table($obj);
    if nqp::existskey(%smt, $name) {
        @meths.push(%smt{$name});
    }
    @meths
}

That way you don't run into trouble with code that expects all types to conform to Mu, but you can still avoid accidentally calling methods from Mu.