![]() This means that if the singleton is never requested, the object is never allocated. One nice property of this approach is that the instance will only be allocated when the GetInstance() method is first called. As a result, one way to initialize our singleton would be to create a static variable inside a method of our class, as follows: Static objects include global objects and objects declared as static inside of a class, function, or a file scope. A non-local object is one that is declared outside of a function. This means that it would be dangerous to initialize our singleton using a non-local static variable. You should therefore prefer returning a reference. However, if you return a pointer, clients could potentially delete the object. ![]() The GetInstance() method could return either a pointer or a reference to the singleton class. (Note, however, that some compilers, such as Borland 5.5 and Visual Studio 6, produce an error incorrectly if you try to declare a destructor as private.) This can be done by declaring the destructor to be private. You want to prevent clients from being able to delete the singleton instance. As seen earlier, this can be done by declaring a private copy constructor and a private assignment operator. You want the singleton to be non-copyable, to enforce that a second instance cannot be created. This can be done by declaring the default constructor to be private, thus preventing the compiler from automatically creating it as public. You don't want clients to be able to create new instances. There are several C++ language features to consider when designing a singleton class. This static method is often called GetInstance(), or similar. The Singleton pattern involves creating a class with a static method that returns the same instance of the class every time it is called. Otherwise, it blocks until the asynchronous result associated with *this is ready, and then returns the value. If the associated state contains a deferred function, invokes the function and returns the return value. Return value in this last case is std::future_status_deferred. Returns immediately if a deferred function call has not yet started execution. Returns std::future_status_timeout in the second case. Returns std::future_status_ready in the first case. Waits until asynchronous result is ready, or until the time delay is elapsed. ![]() Otherwise, it blocks until the asynchronous result associated with *this is ready.įuture_status wait_for(std::chrono::duration const& delay) If the associated state contains a deferred function, invokes the deferred function and stores the return value. Returns true if this is the case, false otherwise. ![]() Read moreĭefines a future not yet associated to an explicit task.Ĭhecks if the future is associated with an asynchronous result. SWIG does provide a way to deal with this by letting you ignore a given overloaded method (using %ignore) or renaming one of the methods (using %rename). For example, SWIG will not be able to disambiguate between overloaded functions that map to the same types in Ruby, for example, a constructor that takes a short and another that takes an int or a constructor that takes a pointer to an object and another that takes a reference to the same type. In general, method overloading is not quite as flexible in Ruby as it is in C++. That is, given the earlier interface file, you can already do: Using SWIG, you simply have to include those constructor declarations in the interface file and it will automatically create the relevant constructors in Ruby. Our Person class has two constructors: a default constructor that takes no parameters and a non-default constructor that takes a std::string name. ![]()
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