英文:
In Go, can both a type and a pointer to a type implement an interface?
问题
例如在下面的例子中：
type Food interface {
Eat() bool
}
type vegetable_s struct {
//一些数据
}
type Vegetable *vegetable_s
type Salt struct {
// 一些数据
}
func (p Vegetable) Eat() bool {
// 一些代码
}
func (p Salt) Eat() bool {
// 一些代码
}
Vegetable和Salt都满足Food接口吗，即使一个是指针，另一个是直接的结构体？
英文:
For example in the following example:
type Food interface {
Eat() bool
}
type vegetable_s struct {
//some data
}
type Vegetable *vegetable_s
type Salt struct {
// some data
}
func (p Vegetable) Eat() bool {
// some code
}
func (p Salt) Eat() bool {
// some code
}
Do Vegetable and Salt both satisfy Food, even though one is a pointer and the other is directly a struct?
答案1
得分: 15
The answer is easy to get by compiling the code:
prog.go:19: invalid receiver type Vegetable (Vegetable is a pointer type)
The error is based on the specs requirement of:
> The receiver type must be of the form T or *T where T is a type name. The type denoted by T is called the receiver base type; it must not be a pointer or interface type and it must be declared in the same package as the method.
(Emphasizes mine)
The declaration:
type Vegetable *vegetable_s
declares a pointer type, ie. Vegetable is not eligible as a method receiver.
英文:
The answer is easy to get by compiling the code:
prog.go:19: invalid receiver type Vegetable (Vegetable is a pointer type)
The error is based on the specs requirement of:
> The receiver type must be of the form T or *T where T is a type name. The type denoted by T is called the receiver base type; it must not be a pointer or interface type and it must be declared in the same package as the method.
(Emphasizes mine)
The declaration:
type Vegetable *vegetable_s
declares a pointer type, ie. Vegetable is not eligible as a method receiver.
答案2
得分: 0
你可以这样做：
package main
type Food interface {
Eat() bool
}
type vegetable_s struct {}
type Vegetable vegetable_s
type Salt struct {}
func (p *Vegetable) Eat() bool {return false}
func (p Salt) Eat() bool {return false}
func foo(food Food) {
food.Eat()
}
func main() {
var f Food
f = &Vegetable{}
f.Eat()
foo(&Vegetable{})
foo(Salt{})
}
英文:
You could do the following:
package main
type Food interface {
Eat() bool
}
type vegetable_s struct {}
type Vegetable vegetable_s
type Salt struct {}
func (p *Vegetable) Eat() bool {return false}
func (p Salt) Eat() bool {return false}
func foo(food Food) {
food.Eat()
}
func main() {
var f Food
f = &Vegetable{}
f.Eat()
foo(&Vegetable{})
foo(Salt{})
}
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