Menene bambanci tsakanin is-a da has-a relationships?

Question

Accepted Answer

**Is-a** shine dangantaka na *nau'i* — da aka ƙera ta hanyar **inheritance** (a `Car` *ne* `Vehicle`). **Has-a** shine dangantaka na *ƙulli* — da aka ƙera ta hanyar **composition** (a `Car` *yana da* `Engine`). Zaɓar daidai shine shaɓa-shaɓar tsarawa.

## Dangantakun biyu

```java
// IS-A → inheritance
class Vehicle { void move() {} }
class Car extends Vehicle { }        // a Car IS A Vehicle

// HAS-A → composition
class Engine { void start() {} }
class Car2 {
    private Engine engine = new Engine();   // a Car HAS AN Engine
    void start() { engine.start(); }        // delegate to the part
}
```

## Gwajin gida

Tanbaya: "Shin X *nau'i ne na* Y, ko X *yana da/yana amfani da* Y?"

```text
A Dog        IS-A Animal        → inheritance ✅
A Car        HAS-A Engine       → composition ✅
A Square     IS-A Shape         → inheritance ✅
A Manager    HAS Employees      → composition (a list) ✅
A Stack      HAS-A list (not IS-A) → composition (see earlier pitfall) ✅
```

## Ƙanƙara

Jama'a sukan nufo ga inheritance don *sake amfani da lambar*, ko da yake dangantaka shine is-a. Idan ba za ku iya maye gurbin subclass ga tushe a ko'ina ba, zaɓi ba shi ba ne is-a — yi amfani da composition.

## Menene mahimmancin

Warin bambanci shine kwakwalwa na amfani a bayan "fi composition girma fiye da inheritance": zaɓi dangantaka da ta yace gaskiya, ba ta da wanda ke kaiwa.

Samun daidai aiki yana toshe gidaje na gajere kuma sautin, kuma yana toshe Liskov violations inda "subtype" ba za ta iya tsaye ajiye ga iyayenta ba.