即使p是指向结构的指针，Go在哪里定义p.Field(与(* p).Field相对)还是有效的语法? [英] Where does Go define that p.Field (as opposed to (*p).Field) is a valid syntax even when p is a pointer to a struct?

问题描述

这是我的Go程序.

package main

import (
    "fmt"
)

type Person struct {
    Name string
}

func main() {
    p := &Person{"Jack"}

    // The following statement makes sense. We dereference the
    // pointer to reach the Person object and then retrieve its Name
    // field.
    fmt.Println((*p).Name)

    // But the following statement does not make sense. How does
    // this code work by retrieving the Name field directly from the
    // pointer without dereferencing it?
    fmt.Println(p.Name)
}

这是输出.

$ go run foo.go 
Jack
Jack

当 p 的类型为 * Person ，即指向 Person 的指针时，访问其字段 Name的合法性不用取消引用吗?我看到了所有使用语法 p.Name 而不是(* p).Name 的Go教程，但是Go语言确切地定义了 p.Person 作为法律语法?

When p is of type *Person, i.e. a pointer to Person, how is it legal to access its field Name without dereferencing it? I see all Go tutorials using the syntax p.Name instead of (*p).Name but where exactly the Go language defines p.Person as a legal syntax?

推荐答案

规范:选择器:

以下规则适用于选择器:

The following rules apply to selectors:

[...]，如果 x 的类型是命名的指针类型，而(* x).f 是表示字段的有效选择器表达式(但不是)一个方法)， xf 是(* x).f 的简写.

[...] if the type of x is a named pointer type and (*x).f is a valid selector expression denoting a field (but not a method), x.f is shorthand for (*x).f.

语言规范可帮助您使用指针语法，以使您感觉在某些情况下甚至没有使用指针.解引用指针以访问其字段是其中之一.如果可以寻址，也可以调用在非指针值上具有指针接收器的方法，请参见

The language spec helps you with the pointer syntax to make it feel you're not even using pointers in some cases. Dereferencing a pointer to access its field is one of them. Also you can call methods that have pointer receiver on non-pointer values if they are addressable, see Calling a method with a pointer receiver by an object instead of a pointer to it?

您还可以索引和切片数组指针，例如如果 a 是指向数组类型的指针:

Also you can index and slice array pointers, e.g. if a is a pointer to array type:

• a [x] 是(* a)[x]
的简写
• 和 a [low:high] 是(* a)[low:high] 的简写.

• a[x] is shorthand for (*a)[x]
• and a[low : high] is shorthand for (*a)[low : high].

这篇关于即使p是指向结构的指针，Go在哪里定义p.Field(与(* p).Field相对)还是有效的语法?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！