Deleter.hh

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#ifndef NO_PTR_DELETER_H
#define NO_PTR_DELETER_H

namespace NoPtr
{
    namespace NoPtrImpl
    {

    /*  Used by DynObj and DynTmp so that ObjType gets deleted in 
        code section where complete definition is visible. This 
        allows them to support declaring OjbType without a full 
        definition, and support the e.g. the pimpl idioim. 
        
        The only necessary design aspect of this class is that 
        the function pointer for the deleter function must be 
        created only in the constructor of the class. Indeed, 
        this is the requirement for the pimpl idiom: the constructor
        must be defined in the source file, at which place the 
        full definition of ObjType is visible, hence the delete works.
        Here, we use a static variable and a static function that gets
        called only once to minimize the impact of this feature on the
        creation time for DynObj and DynTmp. 
        */
    template <typename ObjType>
    class Deleter
    {
        protected: 
            // just set the pointer to deleter once in whole program run
            Deleter() { static const bool inited = initStatic(); }
            // call the deleter on \a ptr
            static void destroy(ObjType* ptr) { (*_deleteObj)(ptr); }
            
        private: 
            // init the static pointer to deleter function
            static bool initStatic() 
            {
                _deleteObj = &Deleter<ObjType>::callDelete;
                return true;
            }
            
            // method to call delete operator to support pimpl
            static inline void callDelete(ObjType* ptr) {delete ptr;}
            
            // typedef for function
            typedef void (*DeleteFn)(ObjType*);
            // the pointer to the function to use for deletion
            static DeleteFn _deleteObj; 
    };
    
    // Fundamental type, so safe use even from inline
    template <typename ObjType> 
    typename Deleter<ObjType>::DeleteFn Deleter<ObjType>::_deleteObj;
            
    } // implementation namespace
    
}

#endif // NO_PTR_DELETER_H

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