Singleton Collection

いろんな言語でSingletonを実装してみると言語ごとの違いがよく出て面白い。 ただ、C言語はかなりノリで作ったものなので、こうこともできるという参考ということで。

	#include <stdio.h>
	#include <stdlib.h>
	typedef struct singleton{
	int id;
	struct singleton* (*getInstance)();
	} Singleton;
	static Singleton *instance;
	Singleton *getInstance(){
	if(instance == NULL){
	instance = (Singleton *)malloc(sizeof(Singleton));
	}
	return instance;
	}
	Singleton* createSingleton(){
	Singleton *instance = getInstance();
	instance->getInstance = getInstance;
	return instance;
	}
	int main(){
	Singleton *s1 = createSingleton();
	Singleton *s2 = createSingleton();
	s1->getInstance()->id=10;
	s2->getInstance()->id=20;
	Singleton *obj = s1->getInstance();
	//if obj->id is 20, it may be singleton.
	printf("%d",obj->id );
	}

view raw singleton.c hosted with ❤ by GitHub

	final class Singleton{
	private static Singleton instance;
	private Singleton(){}
	public static synchronized Singleton getInstance(){
	if(instance == null){
	instance = new Singleton();
	}
	return instance;
	}
	}

view raw Singleton.java hosted with ❤ by GitHub

	var Singleton = (function(){
	var instance;
	function init(){
	return {}
	}
	return {
	getInstance: function(){
	if(!instance){
	instance = init();
	}
	return instance;
	}
	}
	})();

view raw singleton.js hosted with ❤ by GitHub