英文:
Go: How to format this struct in a readable way?
问题
我有一个包装了time.Time对象的结构体，并希望以可读的方式格式化它。
package main
import (
"time"
"fmt"
)
type TimeStruct struct {
t time.Time
}
func main() {
t := time.Now()
fmt.Printf("time: %v\n", t) // nice
ts := TimeStruct{t: t}
fmt.Printf("time struct: %#v\n", ts) // ugly
}
为什么Go不像普通的time.Time对象一样格式化TimeStruct中的t字段？有没有一种简单的方法可以以可读的方式格式化它（而不需要定义额外的方法）？
英文:
I have a struct wrapping a time.Time object and would like to format it in a human readable way.
package main
import (
"time"
"fmt"
)
type TimeStruct struct {
t time.Time
}
func main() {
t := time.Now()
fmt.Printf("time: %v\n", t) // nice
ts := TimeStruct{t: t}
fmt.Printf("time struct: %#v\n", ts) // ugly
}
(Play)
Why doesn't Go format the t field in TimeStruct the same as a plain time.Time object? Is there a simple way to format this in a readable way (without defining extra methods for it)?
答案1
得分: 3
你可以通过实现Stringer接口来获得使用%v时所需的可读时间。
package main
import (
"time"
"fmt"
)
type TimeStruct struct {
t time.Time
}
func (self TimeStruct) String() string {
return fmt.Sprintf("TimeStruct{time.Time: %v}", self.t)
}
func main() {
t := time.Now()
ts := TimeStruct{t: t}
// time struct: TimeStruct{time.Time: 2009-11-10 23:00:00 +0000 UTC}
fmt.Printf("time struct: %v\n", ts)
}
以上是实现的代码部分。
英文:
The only way for you to get the human readable time you want when using %v is to implement the Stringer interface.
package main
import (
"time"
"fmt"
)
type TimeStruct struct {
t time.Time
}
func (self TimeStruct) String() string {
return fmt.Sprintf("TimeStruct{time.Time: %v}", self.t)
}
func main() {
t := time.Now()
ts := TimeStruct{t: t}
// time struct: TimeStruct{time.Time: 2009-11-10 23:00:00 +0000 UTC}
fmt.Printf("time struct: %v\n", ts)
}
答案2
得分: 1
另一种选择是嵌入时间，这样它的方法就可以在你的TimeStruct上使用（playground），例如：
type TimeStruct struct {
time.Time
}
func main() {
t := time.Now()
fmt.Printf("time: %v\n", t)
ts := TimeStruct{Time: t}
fmt.Printf("time struct: %v\n", ts)
}
输出结果为：
time: 2009-11-10 23:00:00 +0000 UTC
time struct: 2009-11-10 23:00:00 +0000 UTC
请注意使用%v而不是%#v，后者会打印结构体成员。
英文:
Another alternative would be to embed the time, so its methods are available on your TimeStruct (playground), eg
type TimeStruct struct {
time.Time
}
func main() {
t := time.Now()
fmt.Printf("time: %v\n", t)
ts := TimeStruct{Time: t}
fmt.Printf("time struct: %v\n", ts)
}
Which prints
time: 2009-11-10 23:00:00 +0000 UTC
time struct: 2009-11-10 23:00:00 +0000 UTC
Note the use of %v not %#v which will print the struct members.
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