golang fmt.Stringer 接口的使用

╰+攻爆jí腚メ 2022-06-07 03:08 246阅读 0赞

在python中，可以通过\_*str*\_()定义输出对象的信息。同样的，在Go中Stringer接口也有此功能。Stringer接口定义在fmt包中，该接口包含String()方法。任何类型只要定义了String()方法，进行Print输出时，就可以得到定制输出。

Stringer接口定义如下：

type Stringer interface {
        String() string
    }

下面通过一些例子加以说明。

\#\#example1

package main
    
    import (
            "fmt"
    )
    
    
    type Power struct{
            age int
            high int
            name string
    }
    
    //指针类型
    func (this *Power) String() string {
            return fmt.Sprintf("age:%d, high:%d, name:%s", this.age, this.high, this.name)
    }
    
    
    func main() {
            var i *Power = &Power{age: 10, high: 178, name: "NewMan"}  //指针类型
    
    
            fmt.Printf("%s\n", i)
            fmt.Println(i)
            fmt.Printf("%v", i)
    }

output:

> age:10, high:178, name:NewMan  
> age:10, high:178, name:NewMan  
> age:10, high:178, name:NewMan

\#\#example2

package main
    
    import (
            "fmt"
    )
    
    
    type Power struct{
            age int
            high int
            name string
    }
    //非指针
    func (this Power) String() string {
            return fmt.Sprintf("age:%d, high:%d, name:%s", this.age, this.high, this.name)
    }
    
    
    func main() {
            var i Power = Power{age: 10, high: 178, name: "NewMan"} //非指针变量
    
            fmt.Printf("%s\n", i)
            fmt.Println(i)
            fmt.Printf("%v", i)
    }

output:

> age:10, high:178, name:NewMan  
> age:10, high:178, name:NewMan  
> age:10, high:178, name:NewMan

\#\#example3

package main
    
    import (
            "fmt"
    )
    
    type Power struct{
            age int
            high int
            name string
    }
    //非指针类型
    func (this Power) String() string {
            return fmt.Sprintf("age:%d, high:%d, name:%s", this.age, this.high, this.name)
    }
    
    
    func main() {
            var i *Power = &Power{age: 10, high: 178, name: "NewMan"}//指针类型
    
            fmt.Printf("%s\n", i)
            fmt.Println(i)
            fmt.Printf("%v", i)
    }

output:

> age:10, high:178, name:NewMan  
> age:10, high:178, name:NewMan  
> age:10, high:178, name:NewMan

\#\#example4

package main
    
    import (
            "fmt"
    )
    
    
    type Power struct{
            age int
            high int
            name string
    }
    
    //指针类型
    func (this *Power) String() string {
            return fmt.Sprintf("age:%d, high:%d, name:%s", this.age, this.high, this.name)
    }
    
    
    func main() {
    
            var i Power = Power{age: 10, high: 178, name: "NewMan"} //非指针
    
            fmt.Printf("%s\n", i)
            fmt.Println(i)
            fmt.Printf("%v", i)
    }

output:

> \{%!s(int=10) %!s(int=178) NewMan\}  
> \{10 178 NewMan\}  
> \{10 178 NewMan\}

此时的输出并不是我们想要的，所以这个用法不可行。