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copied!<p>There are a few things worth noting:</p> <p>Practically speaking, you are not leaking memory. Only a single instance of the class can be created (meaning there is no way the leak can lead to excessive resource use) and the memory allocated to that instance will be reaped by the OS when the client process terminates.</p> <p>The simplest way to make sure the singleton instance is deleted during program termination, as opposed to reaped by the OS, is just to use a static instance with function scope:</p> <pre><code>template<class T> struct Singleton { static T& instance() { static T instance_; return instance_; } }; class SingletonClient : public Singleton<SingletonClient> { friend class Singleton<SingletonClient>; SingletonClient() {} }; SingletonClient &s = Singleton<SingletonClient>::instance(); </code></pre> <p>There is some subtlety to implementing singletons with templates. If you use a singleton template instantiation in multiple translation units then you might actually end up with more than one instance of the singleton client when you really only wanted one. The way to deal with this is to use an extern template declaration in the header file of the client class and a template instantiation in the implementation file of the client.</p> <pre><code>// In header file of SingletonClient: extern template class Singleton<SingletonClient>; // In the implementation file of SingletonClient: template class Singleton<SingletonClient>; </code></pre>

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