将枚举转换为类层次结构 [英] Converting enum into a class hierarchy

问题描述

假设我在Cocoa中编写一个类作为服务器的代理。要表示连接的当前状态，请考虑枚举：

 枚举
 {
 MyConnectionStatusDisconnected = 0 ，
 MyConnectionStatusConnecting，
 MyConnectionStatusConnected，
 MyConnectionStatusCount 
}; 
 typedef NSUInteger MyConnectionStatus; 
  

我可能会像我这样在我的代理类中存在：

  @interface ServerProxy：NSObject 
 {
 MyConnectionStatus connectionStatus; 
} 
  

没关系，但是如果我想找出一个用户可读的解释的连接状态？我可能会有这样的静态函数：

  +（NSString *）statusStringForInt：（MyConnectionStatus）status; 
  

在这一点上，我很快就离开了面向对象编程的领域。

将此枚举重构为类层次结构的最佳方式是什么？

解决方案

我不会将其重构为类层次结构。而是使用NSString常量：

  // foo.h 
 extern NSString * MyConnectionStatusDisconnected; 
 
 
 // foo.m 
 MyConnectionStatusDisconnected = @连接状态：已断开连接; 
  

isEqualToString：将指针相等作为第一个测试，这样会很快。

然后可以使用您的字符串文件中的连接状态：断开连接如果您需要本地化。

Let's say I am writing a class in Cocoa to act as a proxy to a server. To represent the current state of the connection, consider the enumeration:

enum
{
    MyConnectionStatusDisconnected = 0,
    MyConnectionStatusConnecting,
    MyConnectionStatusConnected,
    MyConnectionStatusCount
};
typedef NSUInteger MyConnectionStatus;

I may have it live in my proxy class like so:

@interface ServerProxy : NSObject
{
    MyConnectionStatus connectionStatus;
}

That's fine, but what if I want to figure out a user-readable interpretation of the connection status? I might have a static function like this:

+(NSString*)statusStringForInt:(MyConnectionStatus)status;

At this point I'm quickly leaving the realm of object-oriented programming.

What would be the best way to refactor this enum into a class hierarchy?

解决方案

I wouldn't refactor it into a class hierarchy. Instead, use NSString constants:

// foo.h
extern NSString *MyConnectionStatusDisconnected;


// foo.m
MyConnectionStatusDisconnected = @"Connection Status: Disconnected";

isEqualToString: does pointer equality as the first test so this will be fast.

You can then use Connection Status: Disconnected in your strings file(s) if you need to localize.

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