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    <p>As ever for this sort of subject, there is no answer that applies to every problems. Some said that singleton should be avoided when they are used as an access to a service. It is a use that is akin to the use of global variables. This way you mask the fact that you use service X in your implementation :</p> <pre><code>// in header class MyUsefulClass { public: void doSomethingUseful(); }; // in .cpp MyUsefulClass::doSomethingUseful() { // ... MyWonderfulService::instance().doService1(); // ... MyWonderfulService::instance().doService2(); } </code></pre> <p>You create a coupling with MyWonderfulService that the users of your class can not guess. Moreover, You can not easily test your useful class with a mock service ...</p> <p>That's why I usually prefer <a href="http://en.wikipedia.org/wiki/Dependency_inversion_principle" rel="nofollow">dependancy inversion</a> :</p> <pre><code>// in header class MyUsefulClass { public: void setServiceToUse(MyService&amp;); void doSomethingUseful(); // [...] }; // in .cpp MyUsefulClass::doSomethingUseful() { // ... _myService-&gt;doService1(); // ... _myService-&gt;doService2(); } </code></pre> <p>This way is usually considered better as the coupling between class is lighter. Nevertheless, for some services, which are well known to be of widespread use in a framework, it is simplier to use a singleton. It makes sense for a single service that is the service which give you access to all other services in a framework for example ^^ It is often use for technical services like logging for instance.</p> <p>my2c</p> <p>Edit: I read the article, as the focus is on AbstractFactories, the use of a singleton is a casual one, not a design decision. It is understandable in an article in which you do not want to write things that will not get you to your point.</p>
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    1. COSo to have the autoregistration as shown in the article i need the global access but i don't need it to be the only instance. An alternative would therefore be to provide it as a global like std::cout which alows me to use it, but doen't prevent me from using a second one if needed. Or is there a third way, maybe superior way to achieve this autoregistration?
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    2. CO@p3trus: I will add a concrete example in my answer when I have time ... Just try a global for now. I personnaly use depandancy inversion everytime ...
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