字符串操作

    @name = "hello"
    # 返回@name的值
    puts instance_variable_get("@name")  # => hello
    puts @name  # => hello
    # 设置@name的值 @name = "world"
    puts instance_variable_set("@name", "world")  # => world
    puts @name  # => world
    space = Space.find(params[:id])
    # 设置space.nickname的值 space.nickname = "jack"
    space.send("nickname=","jack")
    # 返回space.nickname的值
    puts space.send("nickname")  # => jack
    # string复数化
    puts "country".pluralize  # => countries
    # string单数化
    puts "posts".singularize  # => post
    # 将表名转成class名
    puts "blog_pictures".classify  # => BlogPicture
    # 将class名转成表名
    puts "BlogPicture".tableize    # => blog_pictures
    # 将class名转成class
    puts "Space".constantize       # => Space
    # 可以将classify和constantize联用，将string转成class model
    puts "spaces".classify.constantize.find(params[:id]).user_type  # => admin