Is there a fragile base class issue in Go?

Question

Despite using composition over inheritance?

If so, is there any solution for it at the language level?

Answer 1

As VonC wrote, but I would like to point out something.

The problem of a fragile base class is often blamed on virtual methods (dynamic method dispatch - this means that if methods can be overridden, the actual implementation that should be called in the case of such an overridden method can only be determined at run time).

? , - , MethodA() MethodB(), , MethodB(), , - , MethodB().

Go , polymorphism. , set , "" . , , wrapper , , , "" , .

- , Go.

Java

. Java, Java "" . Counter MyCounter:

class Counter {
    int value;

    void inc() {
        value++;
    }

    void incBy(int n) {
        value += n;
    }
}

class MyCounter extends Counter {
    void inc() {
        incBy(1);
    }
}

MyCounter:

MyCounter m = new MyCounter();
m.inc();
System.out.println(m.value);
m.incBy(2);
System.out.println(m.value);

, :

1
3

. , , Counter.incBy() :

void incBy(int n) {
    for (; n > 0; n--) {
        inc();
    }
}

Counter - . MyCounter : MyCounter.inc() Counter.incBy(), inc(), - MyCounter.inc()... ... . .

Go

, Go:

type Counter struct {
    value int
}

func (c *Counter) Inc() {
    c.value++
}

func (c *Counter) IncBy(n int) {
    c.value += n
}

type MyCounter struct {
    Counter
}

func (m *MyCounter) Inc() {
    m.IncBy(1)
}

:

m := &MyCounter{}
m.Inc()
fmt.Println(m.value)
m.IncBy(2)
fmt.Println(m.value)

( Go Playground):

1
3

Counter.Inc() , Java:

func (c *Counter) IncBy(n int) {
    for ; n > 0; n-- {
        c.Inc()
    }
}

, . Go Playground.

, , MyCounter.inc() Counter.incBy(), inc(), inc() Counter.Inc(), . Counter MyCounter, MyCounter.

Answer 2

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