Doing weird stuff with Go generics

generics.go

// ~/go/bin/go1.18beta2
package main

type Closeable interface {
	Close() error
}

type CloseableChan[T any] struct {
	ch chan T
}

func NewCloseableChan[T any](ch chan T) *CloseableChan[T] {
	return &CloseableChan[T]{
		ch: ch,
	}
}

func (cc *CloseableChan[T]) Close() (err error) {
	close(cc.ch)
	return
}

func CloseAll(closeable ...Closeable) (err error) {
	for _, cl := range closeable {
		if err = cl.Close(); err != nil {
			return
		}
	}
	return
}

func main() {
	a := NewCloseableChan(make(chan string))
	b := NewCloseableChan(make(chan bool))
	c := NewCloseableChan(make(chan error))

	err := CloseAll(a, b, c)
	if err != nil {
		panic(err)
	}
}