Ruby has some idioms that are used pretty commonly, but not very often understood.array.map(&:method_name)is one of them. We can see it being used everywhere to call a method on everyarrayelement, but why does
[1,2,3].map(&method(:myinc))#=> [2,3,4]# 在 Ruby 源文件的顶层定义的函数属于 Object 对象,所以上面的调用相当于: #[1,2,3].map(&Object.method(:myinc)) 总结 block为 Proc 的语法糖衣,用于单次使用时 Proc专为函数式编程设计,与其他动态语言的函数等价 Method专为面向对象设计,消息传递的...
您能为Ruby中的map(&:Method)语法提供参数吗? 您可能熟悉以下Ruby速记(a是一个数组): a.map(&:method) 例如,在IRB中尝试以下内容: >> a=[:a, 'a', 1, 1.0]=> [:a, "a", 1, 1.0]>> a.map(&:class)=> [Symbol, String, Fixnum, Float] 语法a.map(&:class)是一个缩写a.map {|x| ...
Line 2: We use the [] operator on the hash, which is syntactic sugar for the Hash#[] method. We pass in the integer 0 as the argument for this method. Because there is no key with the value 0 in our hash, the method returns the default value (our single empty array object). We...
Array.each { |index| print Array[index] } Block的定义方式有两种,一种是{},另外一种是do/end。前一种比较适合编写单行程序时使用,后一种比较适合多行程序的情况。具体例子如下: def greet(name) print "Hello #{name} " yield end greet("Wang") do print "Hi" end ...
和Python一样,在Ruby中,…有一个交互提示 (叫做 irb).你可以在命令行中读取文档 (通过ri 命令来替代 pydoc).没有特殊的结束一行的符号(新行除外).文字可以用多行,就像Python中的三个引号.List用[],Dict用{} (Dict在Ruby中叫“hashes”).Arrays的工作方式相同(2个Array相加成为一个更加长的Array,但是想这...
根据SELECT 语句从关系数据生成 XML。它返回 CLOB。 1. 在终端窗口中,通过执行以下命令来执行xml.rb脚本: ruby xml.rb 其输出显示在屏幕截图中。 返回主题列表 9. 使用 ActiveRecord 1. 在终端窗口中,通过执行以下命令来执行activerecord.rb脚本: ruby activerecord.rb ...
OtherArray-like methods like#select,#map,#shuffle,#uniq,#reverse,#rotate,#flatten,#sort,#sort_by,#take,#drop,#take_while,#drop_while,#fill,#product, and#transposeare also supported. See theAPI documentationfor details on allVectormethods. ...
Parallel map is the simplest way to get started with the Workers gem. It is similar to Ruby's built-in Array#map method except each element is mapped in parallel. Workers.map([1,2,3,4,5]){|i|i*i} Any exceptions while mapping with cause the entire map method to fail. If your bl...
attr_reader users: Array[User | Bot] # `|` means union types, `User` or `Bot`. def initialize: (String) -> void def post: (String, from: User | Bot) -> Message # Method overloading is supported. | (File, from: User | Bot) -> Message ...