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  • Ruby 里的 %Q, %q, %W, %w, %x, %r, %s, %i

    %Q

    用于替代双引号的字符串. 当你需要在字符串里放入很多引号时候, 可以直接用下面方法而不需要在引号前逐个添加反斜杠 (")

    >> %Q(Joe said: "Frank said: "#{what_frank_said}"")
    => "Joe said: "Frank said: "Hello!"""
    

    (...)也可用其他非数字字母的符号或成对的符号代替, 诸如[...]!...!+...+,{...}<...>等.

    以下写法全部与上面等效:

    >> %Q!Joe said: "Frank said: "#{what_frank_said}""!
    >> %Q[Joe said: "Frank said: "#{what_frank_said}""]
    >> %Q+Joe said: "Frank said: "#{what_frank_said}""+
    

    除此之外还可省略Q写作:

    >> %/Joe said: "Frank said: "#{what_frank_said}""/
    => "Joe said: "Frank said: "Hello!""" 
    

    %q

    %Q类似, 但是表示的是单引号字符串

    >> %q(Joe said: 'Frank said: '#{what_frank_said} ' ')
    => "Joe said: 'Frank said: '#{what_frank_said} ' '"    
    

    %W

    语法近似于%Q, 用于表示其中元素被双引号括起的数组.

    >> %W(#{foo} Bar Bar with space)
    => ["Foo", "Bar", "Bar with space"] 
    

    %w

    用于表示其中元素被单引号括起的数组. 比较奇怪的是(斜杠空格)会被转化成(空格), 但是其他的内容不会.

    >> %w(a b c d #e #{1}f)
    => ["a", "b", "c d", "\#e", "#{1}f"]
    

    %x

    使用`方法执行一段shell脚本并返回标准输出内容.

    >> %x(echo foo:#{foo})
    => "foo:Foo
    "    
    

    %r

    语法近似于%Q, 用于正则表达式.

    >> %r(/home/#{foo})
     => "/\/home\/Foo/"     
    

    %s

    用于表示symbol, 但是不会对其中表达式等内容进行转化

    >> %s(foo)
    => :foo
    >> %s(foo bar)
    => :"foo bar"
    >> %s(#{foo} bar)
    => :"#{foo} bar"
    

    %i

    Ruby 2.0 之后引入的语法, 用于生成一个symbol数组

    2.0.0p247 :014 > %i(a b c)
    => [:a, :b, :c] 


    原文地址:https://ruby-china.org/topics/18512

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  • 原文地址:https://www.cnblogs.com/stellar/p/5724767.html
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