C ++一个单例类与dll [英] C++ a singleton class with dll

问题描述

我用类创建了一个静态库：

I created a static library with class:

class CLog
{
   private:
   CLog();
   ...
   ...
   public:
   static CLog& GetInstance()                                
   {
           static CLog Instance;
           return Instance;
   }
   void Write(char *cpPr);
};
#define Log CLog::GetInstance()

此库链接到dll，主程序。 dll由LoadLibrary加载。在这种情况下，很明显，在主exe和dll中调用Log.Write，创建两个单独的CLog实例。任何想法如何解决这个问题，仍然提供动态加载dll？

This library is linked to a dll and a main program. The dll is loaded by LoadLibrary. In this case is obvious that calling Log.Write in a main exe and in dll, creates two separate instances of CLog. Any ideas how to work around this issue and still provide dynamic loading a dll?

推荐答案

问题是，静态库，无论是主程序还是DLL，都会得到一个单独的静态变量副本。这打破了创建单例的典型方法。

The problem is that every project that links the static library, be it main program or DLL, will get a separate copy of the static variable. This breaks the typical method of creating a singleton.

最简单的方法是创建另一个包含单例的DLL，而不是静态库。因为只有一个链接器输出将包含静态变量，所以问题就解决了。

The simplest way around this is to create another DLL which holds the singleton, rather than a static library. Since only one linker output will contain the static variable, the problem is solved.

在我自己的例子中，我创建了一个singleton管理器，只有一个副本存在应用程序。单例管理器存在为它自己的DLL。

In my own case I created a singleton manager that identified each singleton by a unique GUID and ensured that only one copy existed application wide. The singleton manager existed as its own DLL.

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