6.3 注释

Go语言中,注释有两种形式:

  1. 行注释:使用双斜线 // 开始,一般后面紧跟一个空格。行注释是Go语言中最常见的注释形式,在标准包中,一般都采用行注释,建议采用这种方式。
  2. 块注释:使用 /* */,块注释不能嵌套。块注释一般用于包描述或注释成块的代码片段。

一般而言,注释文字尽量每行长度接近一致,过长的行应该换行以方便在编辑器阅读。注释可以是单行,多行,甚至可以使用doc.go文件来专门保存包注释。每个包只需要在一个go文件的package关键字上面注释,两者之间没有空行。对于变量,函数,结构体,接口等的注释直接加在声明前,注释与声明之间没有空行。例如:

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:generate go run genzfunc.go
// Package sort provides primitives for sorting slices and user-defined
// collections.
package sort
// A type, typically a collection, that satisfies sort.Interface can be
// sorted by the routines in this package. The methods require that the
// elements of the collection be enumerated by an integer index.
type Interface interface {
	// Len is the number of elements in the collection.
	Len() int
	// Less reports whether the element with
	// index i should sort before the element with index j.
	Less(i, j int) bool
	// Swap swaps the elements with indexes i and j.
	Swap(i, j int)
}
// Insertion sort
func insertionSort(data Interface, a, b int) {
	for i := a + 1; i < b; i++ {
		for j := i; j > a && data.Less(j, j-1); j-- {
			data.Swap(j, j-1)
		}
	}
}

函数或方法的注释需要以函数名开始,且两者之间没有空行,示例如下:

// ContainsRune reports whether the rune is contained in the UTF-8-encoded byte slice b.
func ContainsRune(b []byte, r rune) bool {
	return IndexRune(b, r) >= 0
}

需要预格式化的部分,直接加空格缩进即可,示例如下:

// For example, flags Ldate | Ltime (or LstdFlags) produce,
//	2009/01/23 01:23:23 message
// while flags Ldate | Ltime | Lmicroseconds | Llongfile produce,
//	2009/01/23 01:23:23.123123 /a/b/c/d.go:23: message

在方法,结构体或者包注释前面加上“Deprecated:”表示不建议使用,示例如下:

// Deprecated: Old 老旧方法,不建议使用
func Old(a int)(int){
    return a
}

注释中,还可以插入空行,示例如下:

// Search calls f(i) only for i in the range [0, n).
//
// A common use of Search is to find the index i for a value x in
// a sorted, indexable data structure such as an array or slice.
// In this case, the argument f, typically a closure, captures the value
// to be searched for, and how the data structure is indexed and
// ordered.
//
// For instance, given a slice data sorted in ascending order,
// the call Search(len(data), func(i int) bool { return data[i] >= 23 })
// returns the smallest index i such that data[i] >= 23. If the caller
// wants to find whether 23 is in the slice, it must test data[i] == 23
// separately.