2018-11-08 Address operators
来源: Wechat discuss
Address_operators
package main
import (
"fmt"
"math"
)
type abser interface {
Abs() float64
}
type onef float64
func (one onef) Abs() float64{
return math.Pi
}
func main(){
var a,b abser
a = &onef(3.14)
aa := onef(3.14)
b = &aa
fmt.Println(a.Abs())
fmt.Println(b.Abs())
}为什么 a = &onef(3.14) 会报错，而 aa := onef(3.14) 是可以的呢？
For an operand x of type T, the address operation &x generates a pointer of type *T to x. The operand must be addressable, that is, either a variable, pointer indirection, or slice indexing operation; or a field selector of an addressable struct operand; or an array indexing operation of an addressable array. As an exception to the addressability requirement, x may also be a (possibly parenthesized) composite literal. If the evaluation of x would cause a run-time panic, then the evaluation of &x does too.
对于类型为 T 的操作数 x，地址操作 ＆x 生成类型为 *T 到 x 的指针。操作数必须是可寻址的，即，变量，指针间接或切片索引操作; 或可寻址结构操作数的字段选择器; 或者可寻址数组的数组索引操作。 作为可寻址性要求的例外，x也可以是（可能带括号的）复合文字。 如果x的评估会导致运行时恐慌，那么＆x的评估也会发生。
For an operand x of pointer type *T, the pointer indirection *x denotes the variable of type T pointed to by x. If x is nil, an attempt to evaluate *x will cause a run-time panic.
对于指针类型* T的操作数x，指针间接* x表示由x指向的类型T的变量。如果x为nil，则尝试评估* x将导致运行时出现紧急情况。