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将成员对象公开为 .NET 中的属性或方法

发布于 2024-07-05 21:30:27 字数 51 浏览 7 评论 0原文

在 .NET 中，如果一个类包含一个类对象成员，那么该成员应该作为属性还是通过方法公开？

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谁把谁当真 2024-07-12 21:30:27

您应该对概念上表示对象状态的任何内容使用属性，只要其检索不是一个昂贵的操作，您应该避免重复使用它。

来自 MSDN：

类库设计者通常必须决定是将类成员实现为属性还是方法。一般来说，方法代表动作，属性代表数据。使用以下指南来帮助您在这些选项之间进行选择。
当成员是逻辑数据成员时使用属性。在下面的成员声明中，Name 是一个属性，因为它是类的逻辑成员。
公共字符串名称 
  得到  
  { 
      返回名称； 
  } 
  放  
  { 
      名称=值； 
  } 
  
在以下情况下使用方法：
该操作是一个转换，例如 Object.ToString。
该操作的成本非常高，您希望告知用户他们应该考虑缓存结果。
使用 get 访问器获取属性值会产生明显的副作用。
连续调用该成员两次会产生不同的结果。
执行顺序很重要。请注意，类型的属性应该能够以任何顺序设置和检索。
该成员是静态的，但返回一个可以更改的值。
该成员返回一个数组。返回数组的属性可能非常具有误导性。通常需要返回内部数组的副本，以便用户无法更改内部状态。再加上用户可以轻松假设它是索引属性这一事实，会导致代码效率低下。在下面的代码示例中，对Methods 属性的每次调用都会创建数组的副本。结果，将在下面的循环中创建该数组的 2n+1 个副本。
Type type = // 获取类型。 
  for (int i = 0; i < type.Methods.Length; i++) 
  { 
     if (type.Methods[i].Name.Equals("text")) 
     { 
        // 执行一些操作。 
     } 
  } 
  
以下示例说明了属性和方法的正确使用。
 类连接 
      { 
         // 以下三个成员应该是属性 
         // 因为它们可以按任何顺序设置。 
         字符串 DNSName {get{};set{};} 
         字符串用户名 {get{};set{};} 
         字符串密码 {get{};set{};} 

         // 下面的成员应该是一个方法 
         // 因为执行顺序很重要。 
         // 该方法必须在之后才能执行  
         // 属性已设置。 
         布尔执行(); 
      } 
  

You should use properties for anything that conceptually represents the object's state, so long as its retrieval isn't an expensive enough operation that you should avoid using it repeatedly.

From MSDN:

Class library designers often must decide between implementing a class member as a property or a method. In general, methods represent actions and properties represent data. Use the following guidelines to help you choose between these options.
Use a property when the member is a logical data member. In the following member declarations, Name is a property because it is a logical member of the class.
public string Name
get 
{
    return name;
}
set 
{
    name = value;
}
Use a method when:
The operation is a conversion, such as Object.ToString.
The operation is expensive enough that you want to communicate to the user that they should consider caching the result.
Obtaining a property value using the get accessor would have an observable side effect.
Calling the member twice in succession produces different results.
The order of execution is important. Note that a type's properties should be able to be set and retrieved in any order.
The member is static but returns a value that can be changed.
The member returns an array. Properties that return arrays can be very misleading. Usually it is necessary to return a copy of the internal array so that the user cannot change internal state. This, coupled with the fact that a user can easily assume it is an indexed property, leads to inefficient code. In the following code example, each call to the Methods property creates a copy of the array. As a result, 2n+1 copies of the array will be created in the following loop.
Type type = // Get a type.
for (int i = 0; i < type.Methods.Length; i++)
{
   if (type.Methods[i].Name.Equals ("text"))
   {
      // Perform some operation.
   }
}
The following example illustrates the correct use of properties and methods.
    class Connection
    {
       // The following three members should be properties
       // because they can be set in any order.
       string DNSName {get{};set{};}
       string UserName {get{};set{};}
       string Password {get{};set{};}

       // The following member should be a method
       // because the order of execution is important.
       // This method cannot be executed until after the 
       // properties have been set.
       bool Execute ();
    }