diamond.ts

class Button {
    click() {
        // TODO Animate the button.
    }
}

class RedButton {
    button = new Button()

    style = {
        color: 'red',
    }

    click() {
        this.button.click()
    }
}

class ConfirmButton {
    button = new Button()
    style = {}

    click() {
        if (confirm('Are you sure?')) {
            this.button.click()
        }
    }
}

class RedConfirmButton {
    confirmButton = new ConfirmButton()
    redButton = new RedButton()

    click() {
        // Use ConfirmButton's behaviour.
        this.confirmButton.click()
    }

    get style() {
        // But RedButton's style.
        return this.redButton.style
    }
}

type AnyButton = RedButton | Button | ConfirmButton | RedConfirmButton