Programmer Humor

You're not wrong but I think when you're teaching someone just having 1 parent and 1 child class makes for a bad example I generally prefer to use something with a lot of different children.

My go-to is exporters. We have the exporter interface, the generic exporter, the accounting exporter and the payroll exporter, to explain it.

At school, the only time I used inheritance was 1 parent (booking) and 1 child (luxury) this is a terrible example imo.

I mostly come to prefer composition, this approach apparently even has a wiki page. But that's in part because I use Rust that forbids inheritance, and don't have such bullshit (from delegation wiki page):

class A {
    void foo() {
        // "this" also known under the names "current", "me" and "self" in other languages
        this.bar();
    }

    void bar() {
        print("a.bar");
    }
}

class B {
    private delegate A a; // delegation link

    public B(A a) {
        this.a = a;
    }

    void foo() {
        a.foo(); // call foo() on the a-instance
    }

    void bar() {
        print("b.bar");
    }
}

a = new A();
b = new B(a); // establish delegation between two objects

Calling b.foo() will result in b.bar being printed, since this refers to the original receiver object, b, within the context of a. The resulting ambiguity of this is referred to as object schizophrenia

Translating the implicit this into an explicit parameter, the call (in B, with a a delegate) a.foo() translates to A.foo(b), using the type of a for method resolution, but the delegating object b for the this argument.

Why would one substitute b as this when called from b.a is beyond me, seriously.