Golang中奇怪的类型定义语法（名称，然后键入，然后是字符串文字） [英] Strange type definition syntax in Golang (name, then type, then string literal)

问题描述

 <$ c我一直在试图找出如何使用mgo（MongoDB for Go）的驱动程序，并且遇到了这个结构声明： $ c> type Something struct {
 Id bson.ObjectId_id，omitempty
 Name string 
} 
  

我不太了解第一个元素（Id）的语法。我知道它被声明为类型 bson.ObjectId ，但是在那里的字符串是什么？

我的问题不是关于mgo驱动程序的功能，而是关于这个奇怪的< name> <类型> < string_literal> 语法。

Go规格中找不到任何内容，我也不知道如何在Google 。 =noreferrer> 语言规范中的Struct types 部分：

字段声明后面可以跟随一个可选的字符串文字
tag ，它成为所有字段的属性相应的字段声明。这些标签通过
反射界面显示，但会被忽略。

  //与TimeStamp协议缓冲区相对应的结构体。 
 //标记字符串定义协议缓冲区字段号。 
 struct {
 microsec uint64field 1
 serverIP6 uint64field 2
 process stringfield 3
} 
  

I've been trying to find out how to use mgo (MongoDB driver for Go) and I came across this struct declaration:

type Something struct {
    Id bson.ObjectId "_id,omitempty"
    Name string
}

I don't quite understand the syntax of the first element (Id). I understand that it's being declared as type bson.ObjectId, but what is the string literal doing there?

My question is not about the mgo driver functionality,
but about this strange <name> <type> <string_literal> syntax.

I couldn't find anything on the Go specs, and I don't know how to google this either.

解决方案

It's explained in the Struct types section of the language specification:

A field declaration may be followed by an optional string literal tag, which becomes an attribute for all the fields in the corresponding field declaration. The tags are made visible through a reflection interface but are otherwise ignored.

// A struct corresponding to the TimeStamp protocol buffer.
// The tag strings define the protocol buffer field numbers.
struct {
    microsec  uint64 "field 1"
    serverIP6 uint64 "field 2"
    process   string "field 3"
}

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