.net - 在 .NET 中将成员对象公开为属性或方法

Question

在 .NET 中，如果一个类包含一个作为类对象的成员，该成员应该作为属性公开还是使用方法公开？

Answer 1

您应该为任何概念上表示对象状态的东西使用属性，只要它的检索不是一个足够昂贵的操作，您应该避免重复使用它。

来自 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 ();
    }