オブジェクト指向はオワコン？ part2

Rustで発生するFragile Base Class Problemの一例

trait PointCalculator {
fn regular_point(&self, payment_amount: i32) -> i32;

fn campaign_point(&self, payment_amount: i32) -> i32 {
self.regular_point(payment_amount) * 2
}

fn super_campaign_point(&self, payment_amount: i32) -> i32 {
self.regular_point(payment_amount) * 4
// self.campaign_point(payment_amount) * 2 //<== こういう変更をすると継承先が壊れる可能性がある
}
}
https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=84769fbdb0fc90ba597cb86c8c2ed9d4