effective-go chapter4

跟C一样，Go 的正式语法使用分号结束语句，但与C不同的是，这些分号在源码中不可见。取而代之的是，词法分析器会使用一个简单的规则，在扫描时自动插入分号，所以输入文本中几乎没有它。

具体规则是这样的。在新的一行之前，最后如果是一个这样的标识符（包括 int 、 float64 ），一个基本的文字，如数字、字符串常量、或者是下面符号中的一个

Like C, Go’s formal grammar uses semicolons to terminate statements, but unlike in C, those semicolons do not appear in the source. Instead the lexer uses a simple rule to insert semicolons automatically as it scans, so the input text is mostly free of them.

The rule is this. If the last token before a newline is an identifier (which includes words like int and float64 ), a basic literal such as a number or string constant, or one of the tokens

break continue fallthrough return ++ -- ) }

词法分析器总会在标记后面插入一个分号。这可以总结为：“如果新的一行紧跟一个语句的结束符，就会插入一个分号”。

也可以在右大括号前省略分号，如下语句

the lexer always inserts a semicolon after the token. This could be summarized as, “if the newline comes after a token that could end a statement, insert a semicolon”.

A semicolon can also be omitted immediately before a closing brace, so a statement such as

go func() { for { dst <- <-src } }()

无需分号。习惯用法是，Go程序只在像 for 循环这样的语句中使用分号，以分割初始化器，条件，延续元素。分号还用于分割一行的多条语句。

插入分号的一个结果是，你不能把控制语句的左大括号放在下一行。如果你确实这样做了，括号前就会插入一个分号，这将导致不可预知的结果。要这样写：

needs no semicolons. Idiomatic Go programs have semicolons only in places such as for loop clauses, to separate the initializer, condition, and continuation elements. They are also necessary to separate multiple statements on a line, should you write code that way.

One consequence of the semicolon insertion rules is that you cannot put the opening brace of a control structure ( if , for , switch , or select ) on the next line. If you do, a semicolon will be inserted before the brace, which could cause unwanted effects. Write them like this

if i < f() {
    g()
}

而不是这样：

not like this

if i < f()  // wrong!
{           // wrong!
    g()
}

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