英文:
Golang: declare a single constant
问题
在Go语言中，声明单个常量的首选方式是哪种？
const myConst
const (
myConst
)
这两种方式都被gofmt接受。这两种方式都可以在stdlib中找到，尽管1)的使用更为广泛。
英文:
Which is the preferred way to declare a single constant in Go?
1)
const myConst
const (
myConst
)
Both ways are accepted by gofmt. Both ways are found in stdlib, though 1) is used more.
答案1
得分: 8
第二种形式主要用于将多个常量声明分组。
如果只有一个常量，第一种形式就足够了。
const maxNanoSecondIntSize = 9
// 压缩方法
const (
Store uint16 = 0
Deflate uint16 = 8
)
这并不意味着你必须将所有常量都放在一个const ()中：当你有通过iota（连续整数）初始化的常量时，每个块都计数。
例如cmd/yacc/yacc.go
// 状态生成的标志
const (
DONE = iota
MUSTDO
MUSTLOOKAHEAD
)
// 规则具有动作和被规约的标志
const (
ACTFLAG = 1 << (iota + 2)
REDFLAG
)
> 这也可以通过import、type、var等方式实现，并且可以多次使用。
这是正确的，但你会发现iota只在常量声明中使用，如果你需要多组连续的整数常量，这将迫使你定义多个const ()块。
英文:
The second form is mainly for grouping several constant declarations.
If you have only one constant, the first form is enough.
for instance archive/tar/reader.go:
const maxNanoSecondIntSize = 9
But in archive/zip/struct.go:
// Compression methods.
const (
Store uint16 = 0
Deflate uint16 = 8
)
That doesn't mean you have to group all constants in one const (): when you have constants initialized by iota (successive integer), each block counts.
See for instance cmd/yacc/yacc.go
// flags for state generation
const (
DONE = iota
MUSTDO
MUSTLOOKAHEAD
)
// flags for a rule having an action, and being reduced
const (
ACTFLAG = 1 << (iota + 2)
REDFLAG
)
dalu adds in the comments:
> it can also be done with import, type, var, and more than once.
It is true, but you will find iota only use in a constant declaration, and that would force you to define multiple const () blocks if you need multiple sets of consecutive integer constants.
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