Ruby6 细节补充

摘要

DemoBuildin Methodsruby中的特殊变量 在irb中可以直接输出，当加载模块的时候ruby会在的各个目录中查找加载,如果查找不到会抛出异常

代码规范

1. 使用UTF-8编码
2. 使用空格缩进，不使用tab, 1 tab = 2 spaces
3. 不需要使用分号(;)和反斜杠()连接代码

Demo

# basic types a = 1 b = "hello world"  # one line c = ["pear", "cat", "dog"]  # or multiple lines c2 = [     "pear",     "cat",     "dog" ]  d = { name:"world", age:18 } d2 = {     name:"world",     age:18 }  # source layout, conversion  # with or without()  def hello(name, age = 18)     puts "hello #{name}, and age is #{age}" end   def hello name, age = 18     puts "hello #{name}, and age is #{age}" end  

变量类型

1. local variables 局部变量: a = 1,b = "hello
2. constants 常量: Names = ['john','alex']
3. global variables 全局变量: $platform = 'mac'
4. instance variables 实例变量: @name = 'world'
5. class variables 类变量: @@counter = 20

# variables scope  # constant Name = 'world' Name = 'worlds' # => output wraning  Name.replace 'world_2'  # => safe puts Name

# instance variable and class variable  class User     # 相当于定义一个get操作：相当于有一个name的实例变量     # 使用attr_reader关键字，实现把内部的实例变量 向外部保留一个访问接口     attr_reader :name      ## 相当于静态变量     @@counter = 0      def initialize name         @name = name          @@counter += 1 #记录实例化次数     end      def get_counter         @@counter     end end  user = User.new 'world' puts user.name puts user.get_counter

# variables scope  # global variables  def hello     puts $$  #=> process id     p $: # => ruby loading path end  hello 

Boolean表达式

1. %%, ||, !
2. And, Or, Not

#boolean clause  puts (true and true) puts (true and false) puts (true or false) puts (not true)

#boolean clause  a = (false and false || true) # 先|| 再and b = (false and false or true) # 优先级相同 先 and 再or  puts a puts b

#boolean clause  a = nil b = a || 4 # 如果a是成立的(不是false和nim) 那么a赋值给b 否则赋值4给b puts b # => 4  c = b && 5 # 如果b成立那么执行 c = 5  puts c # => 5 

#boolean clause  # preference # and or not 优先级 低于 && || ! = a = nil b = a or 4 # or 优先级 低于 = 操作符 所以实际吧a赋值给b 然后 or 4 puts b # => will be nil  c = b && 5 # b是nil 所有 b&&5 不成立 所以 c =nil puts c #=> will be nil

String,Hash和Array常用方法

# string  a = "hello world" a.empty? # => false  a[0] = "a" # => aello world  a.freeze a[0] = "h" # => will raise error  a = "hello" # =>ok, re-assign value 

# string  a = "hello world" a.reverse # => dlrow olleh  # both of these method have ! version  a.sub('o', 'A') # =>hellA world a.gsub('o', 'A') # => hellA wArld  a.start_with? 'h' # => true a.end_with? 'd' # => true a.include? 'o'

# string  a = "hello world" b = a.split(' ') # => ["hello", "world"]  b.join(' ') # => hello world

# string  # variable refer  a = "hello world" b = a # 将字符串的引用地址 或者说指针 给了b puts b  b[0] = "A" puts a # => Aello world  puts '-' * 30  a = "hello world" b = a.dup # what's the difference with String#clone method? 完整复制， 不是引用了  b[0] = "A" puts b  # => Aello world puts a  # => hello world  #output hello world Aello world ------------------------------ Aello world hello world

# array  a = ["pear", "cat", "horse"] puts a.join(' ') # 数组中必须都是字符串 才可以用字符连接  a.clear #清空数组  a.find {|x| x == 'horse'} #查找匹配到的  a.map {|x| x.upcase} # 迭代执行 a.collect {|x| x.upcase} #map方法的别名  a.uniq #排除多余重复 a.flatten #吧二维或者多维转换以为 a.sort #排序 a.count #元素数量  a.delete_if {|x| x == 'horse'} #匹配则删除 a.each {|x| puts x} #遍历

# hash  a = {name: 'world', age: 18}  a.each {|key, value| puts key} #遍历 a.keys # 所有key a.values # 所有value a.has_key? :name #判断是否有key a.delete :name #删除key a.delete_if #匹配则删除

其他

Buildin Methods

1. send:private method and method as a variable #调用私有方法，调用的方法名是个遍历的时候 使用send(元编程)
2. respond_to? #探测实例是否有给定方法
3. demo

# send method  def hello   puts 'hello world' end  send(:hello)

# respond_to?  a = "hello world"  puts a.respond_to?(:length)

代码加载机制

$LOAD_PATH

ruby中的特殊变量 在irb中可以直接输出，当加载模块的时候ruby会在的各个目录中查找加载,如果查找不到会抛出异常

命名约束

ruby中每一个文件都是一个独立的文件。文件名和文件中的类名(模块名)对应

file_name: user_session.rb   class_name: UserSession