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发布于 2024-08-01 21:47:05 字数 578 浏览 4 评论 0原文

我有一个 switch 语句，它一遍又一遍地执行一些逻辑。我想将其放入一个函数中，而不是使用剪切和粘贴，但我在这方面失败了。

这就是我想做的，但它无法编译，因为函数中的break标记不存在。有人可以将其重构为更好的工作版本吗？

switch(param.ToString())
{
  case "1":
  BreakIfNotArgumentType<B>(param);
 //do stuff
  break;
  case "2":
  BreakIfNotArgumentType<BF>(param);
 //do stuff
  break;
}

   private T BreakIfNotArgumentType<T>(object argumentObject)
    {
        if (argumentObject is T)
        {
            return (T)argumentObject;
        }
        else
        {
            break;
        }            
    }

原文

I have a switch statement that executes some logic over and over. Rather then use cut and paste I wanted to put it into a function, but I am failing badly at this.

This is what I want to do, but it does not compile because the break tag in the function does not exist. Can anyone refactor this to a better working version?

switch(param.ToString())
{
  case "1":
  BreakIfNotArgumentType<B>(param);
 //do stuff
  break;
  case "2":
  BreakIfNotArgumentType<BF>(param);
 //do stuff
  break;
}

   private T BreakIfNotArgumentType<T>(object argumentObject)
    {
        if (argumentObject is T)
        {
            return (T)argumentObject;
        }
        else
        {
            break;
        }            
    }

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复古式 2024-08-08 21:47:05

您的函数本质上是复制 as 运算符的功能。

string foo = "foo";

....

object a = foo;
object b = 12;
....

string bar = a as string; // will give you "foo"
string zed = b as string; // returns null

as 运算符充当运行时安全的强制转换。如果目标实例无法转换为目标类型，则分配空引用。因此，它仅适用于引用类型。最常见的用法是这样的...

string bar = a as string;

if(bar != null)
{
    // do stuff
}

因为这在一个语句中给出了类型检查和转换操作。

您应该发布您的 switch 语句，我们也许能够更好地简化它。尝试像您那样编写一个真正的内联函数（您期望它将函数中的代码替换为 switch 语句，这使其更像是宏而不是函数）是行不通的。

Your function is essentially replicating the functionality of the as operator.

string foo = "foo";

....

object a = foo;
object b = 12;
....

string bar = a as string; // will give you "foo"
string zed = b as string; // returns null

The as operator functions as a runtime-safe cast. If the target instance can't be cast to the target type, then a null reference is assigned. Because of this, it will only work with reference types. The most common usage is like this...

string bar = a as string;

if(bar != null)
{
    // do stuff
}

Because this gives the type checking and casting operation in one statement.

You should post your switch statement and we may be able to streamline it better. Trying to write a truly inline function as you had (where you were expecting it to substitute the code in the function into your switch statement, which makes it more of a macro than a function) won't work.

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溺渁∝ 2024-08-08 21:47:05

如果参数无法转换，您可以让函数返回 null，或者抛出异常，以了解如何处理该部分代码的一些想法。

   private T BreakIfNotArgumentType<T>(object argumentObject)
    {
        if (argumentObject is T)
        {
            return (T)argumentObject;
        }
        else
        {
            return null;
        }            
    }

或者

   private T BreakIfNotArgumentType<T>(object argumentObject)
    {
        if (argumentObject is T)
        {
            return (T)argumentObject;
        }
        else
        {
            throw CustomException("Argument wasn't valid!");
        }            
    }

You could have the function return a null if the argument can't be cast or throw an exception for a couple of ideas on how to handle that part of the code.

   private T BreakIfNotArgumentType<T>(object argumentObject)
    {
        if (argumentObject is T)
        {
            return (T)argumentObject;
        }
        else
        {
            return null;
        }            
    }

   private T BreakIfNotArgumentType<T>(object argumentObject)
    {
        if (argumentObject is T)
        {
            return (T)argumentObject;
        }
        else
        {
            throw CustomException("Argument wasn't valid!");
        }            
    }

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国际总奸 2024-08-08 21:47:05

让您的方法返回布尔值并检查返回值：

switch(param.ToString())
{
  case "1":
  if (CheckForArgumentType<B>(param))
  {
   // Do your cast here
   param = (B)param
  }
  else
     break;
  case "2":
  if (CheckForArgumentType<B>(param))
  {
   // Do your cast here
   param = (B)param
  }
  else
     break;
  }
  .................

   private bool CheckForArgumentType<T>(object argumentObject)
    {
        return (argumentObject is T)

    }

Make your method to return a boolean and check the return value:

switch(param.ToString())
{
  case "1":
  if (CheckForArgumentType<B>(param))
  {
   // Do your cast here
   param = (B)param
  }
  else
     break;
  case "2":
  if (CheckForArgumentType<B>(param))
  {
   // Do your cast here
   param = (B)param
  }
  else
     break;
  }
  .................

   private bool CheckForArgumentType<T>(object argumentObject)
    {
        return (argumentObject is T)

    }

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