变量魔术和从文件读取 [英] Variables magic and read from file

问题描述

假设我收到以下文件（ input.txt ）：

  name =彼得
年龄= 26 
 family_status =已婚
  

在一个随机的顺序，谎言：

  family_status =已婚
 name =Peter
年龄= 26 
  

在我的程序中，我还有变量 family_status ， / strong>和名称。如何在单个循环中读取文件中的这些行并为其赋值？

>

这取决于几个事实。

• 你有什么样的变量（局部变量，实例变量，类变量或全局变量）
  
• family_status是什么类型（ String， 符号，无论什么）
  
  
  

  我假设你正在使用实例变量：
  
  

    def read_vars（io，vars）
   io.each do | line | 
  ＃确保行有正确的格式（name = var）
  提升格式错误，除非行=〜/ ^ \s *（\w +）\s * = \s * ？（。*？）？\s + $ / 
   var =：@＃{$ 1}
  ＃选择数据类型
   value = case vars [var] 
  当字符串
   $ 2 
  当整数
   $ 2.to_i 
  当符号
   $ 2.to_sym 
   else 
  提高invalid var 
   end 
   instance_variable_set（var，value）
   end 
   end 
   $ b read_vars（File.read（input.txt，：@age = > Integer，：@name => String，：@family_status => Symbol）
    

  你没有使用实例变量，你必须改变 instacne_variable_set 和 var =：@ ... 这个代码具有以下优点：$ b​​
  $ b

  
  
  • 您可以控制哪些变量可以设置
  
  
  • 控制这些变量的类型是什么
  
  
  • 您可以轻松地添加新的变量您可以使用此代码读取完全不同的文件，而无需为其写入新代码。
  
  / ul>
  
  

  阅读为YAML

  
  
  

  如果您的需求不如您的问题具体，我会采用完全不同的方法到这个。

  
  
  

  我会把 input.txt 写成yaml文件。在yaml语法中，它看起来像这样：
  
  

    --- 
  名称：Peter 
  年龄：26 
   family_status：已婚
    

  您可以阅读：
  
  

    YAML.load（File.read（input.txt））＃=> {name=> 彼得，年龄=> 26，family_status=> ：married} 
    

  如果您不控制 input.txt 文件，您不能控制数据的类型。我将命名文件 input.yaml 而不是 input.txt 。如果你想了解更多，关于如何写yaml文件请看： http：//yaml.kwiki .ORG /？YamlInFiveMinutes 的。关于yaml和ruby的更多信息可以在 http：// www.ruby-doc.org/stdlib/libdoc/yaml/rdoc/index.html 。

  
  

  Assume, i got the following file (input.txt):

  name = "Peter"
  age = 26
  family_status = married
  

  Mentioned lines can be stored in a random order, lie:

  family_status = married
  name = "Peter"
  age = 26
  

  In my program I also have variables family_status, age and name. How do I in a single cycle read those lines from file and assign correspond variables with the values?

  解决方案

  Setting Variables

  This depends on several facts.

  • What kind of variables do you have (local variables, instance variables, class variables, or global variables)
  • What kind of type is family_status (String, Symbol, whatever)

  I assume you are using instance variables for this:

  def read_vars(io, vars)
    io.each do |line|
      # ensure the line has the right format (name = var)
      raise "wrong format" unless line=~ /^\s*(\w+)\s*=\s*"?(.*?)"?\s+$/
      var= :"@#{$1}"
      # pick the type of the data
      value= case vars[var]
      when String
        $2
      when Integer
        $2.to_i
      when Symbol
        $2.to_sym
      else
        raise "invalid var"
      end
      instance_variable_set(var, value)
    end
  end
  
  read_vars(File.read("input.txt", :@age => Integer, :@name => String, :@family_status => Symbol )
  

  If you are not using instance variables you have to change the instacne_variable_set and var= :"@... line to you needs. This code has the following advantages:

  • You control which variables can be set
  • You control which types these variables have
  • You can easily add new variables and/or change types of variables without changing the read code
  • You can use this code to read entirely different files, without writing new code for it

  reading as YAML

  If your needs are not as specific as in your question I would go an entirely different approach to this.

  I would write the input.txt as a yaml file. In yaml syntax it would look like this:

  ---
  name: Peter
  age: 26
  family_status: :married
  

  You can read it with:

  YAML.load(File.read("input.txt")) # => {"name" => "Peter", "age" => 26, "family_status" => :married }
  

  Be carefull if you don't control the input.txt file, you don't control which types the data will have. I would name the file input.yaml instead of input.txt. If you want to know more, about how to write yaml files have a look at: http://yaml.kwiki.org/?YamlInFiveMinutes. More infos about yaml and ruby can be found at http://www.ruby-doc.org/stdlib/libdoc/yaml/rdoc/index.html.

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