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复杂的错误处理(Complex error handling)

 我有一个特别令人讨厌的网络代码。 我正在使用asio，但这对于这个问题并不重要。 我假设除了关闭套接字之外没有办法取消绑定套接字。 问题是open() ， bind()和listen()都可以抛出system_error 。 所以我用一个简单的try/catch处理代码。 代码写得很破碎。  
using namespace boost::asio;

class Thing
{
public:

   ip::tcp::endpoint m_address;

   ip::tcp::acceptor m_acceptor;

   /// connect should handle all of its exceptions internally.
   bool connect()
   {
      try
      {
         m_acceptor.open( m_address.protocol() );
         m_acceptor.set_option( tcp::acceptor::reuse_address(true) );

         m_acceptor.bind( m_address );
         m_acceptor.listen();

         m_acceptor.async_accept( /*stuff*/ );
      }
      catch( const boost::system::system_error& error )
      {
         assert(acceptor.is_open());
         m_acceptor.close();
         return false;
      }
      return true;
   }

   /// don't call disconnect unless connect previously succeeded.
   void disconnect()
   {
      // other stuff needed to disconnect is ommited
      m_acceptor.close();
   }
};
 
 错误是如果套接字连接失败，它将尝试在catch块中关闭它，并抛出另一个关于关闭从未打开的接受器的system_error。  
 一种解决方案是在catch块中添加一个if( acceptor.is_open() ) ，但这种方法错了。 有点像将C风格的错误检查与c++异常混合在一起。 如果我去那条路线，我也可以使用open()的非投掷版本。  
boost::system::error_code error;
acceptor.open( address.protocol, error );
if( ! error )
{
    try
    {
       acceptor.set_option( tcp::acceptor::reuse_address(true) );

       acceptor.bind( address );
       acceptor.listen();

       acceptor.async_accept( /*stuff*/ );
    }
    catch( const boost::system::system_error& error )
    {
       assert(acceptor.is_open());
       acceptor.close();
       return false;
    }
}
return !error;
 
 有没有一种优雅的方法来使用RAII和try/catch块来处理这些可能的异常？  
 在尝试避免使用异常时if( error condition )样式错误处理时，我是错误的吗？ 

I've got a particularly ornery piece of network code. I'm using asio but that really doesn't matter for this question. I assume there is no way to unbind a socket other than closing it. The problem is that open(), bind(), and listen() can all throw a system_error. So I handled the code with a simple try/catch. The code as written in broken. 
using namespace boost::asio;

class Thing
{
public:

   ip::tcp::endpoint m_address;

   ip::tcp::acceptor m_acceptor;

   /// connect should handle all of its exceptions internally.
   bool connect()
   {
      try
      {
         m_acceptor.open( m_address.protocol() );
         m_acceptor.set_option( tcp::acceptor::reuse_address(true) );

         m_acceptor.bind( m_address );
         m_acceptor.listen();

         m_acceptor.async_accept( /*stuff*/ );
      }
      catch( const boost::system::system_error& error )
      {
         assert(acceptor.is_open());
         m_acceptor.close();
         return false;
      }
      return true;
   }

   /// don't call disconnect unless connect previously succeeded.
   void disconnect()
   {
      // other stuff needed to disconnect is ommited
      m_acceptor.close();
   }
};
 
The error is if the socket fails to connect it will try to close it in the catch block and throw another system_error about closing an acceptor that has never been opened. 
One solution is to add an if( acceptor.is_open() ) in the catch block but that tastes wrong. Kinda like mixing C-style error checking with c++ exceptions. If I where to go that route, I may as well use the non-throwing version of open(). 
boost::system::error_code error;
acceptor.open( address.protocol, error );
if( ! error )
{
    try
    {
       acceptor.set_option( tcp::acceptor::reuse_address(true) );

       acceptor.bind( address );
       acceptor.listen();

       acceptor.async_accept( /*stuff*/ );
    }
    catch( const boost::system::system_error& error )
    {
       assert(acceptor.is_open());
       acceptor.close();
       return false;
    }
}
return !error;
 
Is there an elegant way to handle these possible exceptions using RAII and try/catch blocks? 
Am I just wrong headed in trying to avoid if( error condition ) style error handling when using exceptions?

原文：https://stackoverflow.com/questions/2730963

更新时间：2023-11-15 20:11

最满意答案

 此代码适用于您的方案。 但是如果你需要一个泛型函数，它适用于多个嵌套数组，我们需要编写一个递归函数。  
<?php
$json_contents = file_get_contents('test.json'); //Placed your json in test.json 

$output = array();
$json_array = json_decode($json_contents, true); //Convert json to php array 

foreach ($json_array as $element){  
    foreach ($element as $attribute => $value){ //parse through each attribute 
      if(is_array($value)){   //if value is an array, parse through it and update output array accordingly
          foreach ($value as $a => $v) {
            $output[$attribute.'_'.$a] = $v;
          }
      }
      else{      //if value is not an array, get those elements as they are into $output 
          $output[$attribute] = $value;
      }
  }
}
print_r($output);  //You can convert $output into json using json_encode($output);
print_r($json_array);
 
 test.json：  
{
  "company": {
    "name": "Example Co",
    "legalName": "Example Co LLC",
    "domain": "example.com",
    "domainAliases": [
      "example01.com",
      "example02.com",
      "example03.com"
    ],
    "category": {
      "sector": "Financials",
      "industryGroup": "Diversified Financial Services",
      "industry": "Diversified Financial Services",
      "subIndustry": "Financial Services"
    },
    "tags": [
      "Marketplace",
      "B2C",
      "Financial Services"
    ],
    "foundedYear": null,
    "tech": [
      "google_analytics",
      "hotjar",
      "outlook"
    ]
  }
}
 
 输出：  
Array
(
    [name] => Example Co
    [legalName] => Example Co LLC
    [domain] => example.com
    [domainAliases_0] => example01.com
    [domainAliases_1] => example02.com
    [domainAliases_2] => example03.com
    [category_sector] => Financials
    [category_industryGroup] => Diversified Financial Services
    [category_industry] => Diversified Financial Services
    [category_subIndustry] => Financial Services
    [tags_0] => Marketplace
    [tags_1] => B2C
    [tags_2] => Financial Services
    [foundedYear] => 
    [tech_0] => google_analytics
    [tech_1] => hotjar
    [tech_2] => outlook
)

This code works good for your scenario. But if you need a generic function, that works with multiple nested arrays, we need to write a recursive function.  
<?php
$json_contents = file_get_contents('test.json'); //Placed your json in test.json 

$output = array();
$json_array = json_decode($json_contents, true); //Convert json to php array 

foreach ($json_array as $element){  
    foreach ($element as $attribute => $value){ //parse through each attribute 
      if(is_array($value)){   //if value is an array, parse through it and update output array accordingly
          foreach ($value as $a => $v) {
            $output[$attribute.'_'.$a] = $v;
          }
      }
      else{      //if value is not an array, get those elements as they are into $output 
          $output[$attribute] = $value;
      }
  }
}
print_r($output);  //You can convert $output into json using json_encode($output);
print_r($json_array);
 
test.json :  
{
  "company": {
    "name": "Example Co",
    "legalName": "Example Co LLC",
    "domain": "example.com",
    "domainAliases": [
      "example01.com",
      "example02.com",
      "example03.com"
    ],
    "category": {
      "sector": "Financials",
      "industryGroup": "Diversified Financial Services",
      "industry": "Diversified Financial Services",
      "subIndustry": "Financial Services"
    },
    "tags": [
      "Marketplace",
      "B2C",
      "Financial Services"
    ],
    "foundedYear": null,
    "tech": [
      "google_analytics",
      "hotjar",
      "outlook"
    ]
  }
}
 
Output:  
Array
(
    [name] => Example Co
    [legalName] => Example Co LLC
    [domain] => example.com
    [domainAliases_0] => example01.com
    [domainAliases_1] => example02.com
    [domainAliases_2] => example03.com
    [category_sector] => Financials
    [category_industryGroup] => Diversified Financial Services
    [category_industry] => Diversified Financial Services
    [category_subIndustry] => Financial Services
    [tags_0] => Marketplace
    [tags_1] => B2C
    [tags_2] => Financial Services
    [foundedYear] => 
    [tech_0] => google_analytics
    [tech_1] => hotjar
    [tech_2] => outlook
)

复杂的错误处理(Complex error handling)

最满意答案

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