如何在C中创建Singleton？ [英] How to create a Singleton in C?

问题描述

在C中创建单身人士的最佳方法是什么？一个并发解决方案将是很好的。

我知道C不是单身人士使用的第一种语言。

解决方案

首先，C不适合OO编程。如果你这样做，你一直在战斗。其次，单例只是一些封装的静态变量。所以你可以使用一个静态的全局变量。然而，全球变量通常与他们相关的病毒太多。您可以使用本地静态变量函数，如下所示：

  int * SingletonInt（）{
 static int instance = 42; 
 return& instance; 
} 
  

或更聪明的宏：

  #define SINGLETON（t，inst，init）t * Singleton _ ## t（）{\ 
 static t inst = init; \ 
 return& inst; \ 
} 
 
 #include< stdio.h> 
 
 / *实际定义* / 
 SINGLETON（float，finst，4.2）; 
 
 int main（）{
 printf（％f\\\
，*（Singleton_float（）））; 
 return 0; 
} 
  

最后，请记住，单身人士大多被滥用。很难让他们正确，特别是在多线程环境下...

What's the best way to create a singleton in C? A concurrent solution would be nice.

I am aware that C isn't the first language you would use for a singleton.

解决方案

First, C is not suitable for OO programming. You'd be fighting all the way if you do. Secondly, singletons are just static variables with some encapsulation. So you can use a static global variable. However, global variables typically have far too many ills associated with them. You could otherwise use a function local static variable, like this:

 int *SingletonInt() {
     static int instance = 42;
     return &instance;
 }

or a smarter macro:

#define SINGLETON(t, inst, init) t* Singleton_##t() { \
                 static t inst = init;               \
                 return &inst;                       \
                }

#include <stdio.h>  

/* actual definition */
SINGLETON(float, finst, 4.2);

int main() {
    printf("%f\n", *(Singleton_float()));
    return 0;
}

And finally, remember, that singletons are mostly abused. It is difficult to get them right, especially under multi-threaded environments...

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