"Jason Hise" wrote:
I just wanted to get some opinions on the following static allocation policy, revamped to ensure that there won't be alignment problems. Does anything need to be revised?
template < typename Type > class AllocateStatically { public: typedef Type * Pointer;
static Pointer Create ( ) { static Type instance; static bool first = true;
if ( first ) { first = false; } else { new ( reinterpret_cast < Pointer > ( &instance ) ) Type; }
return &instance; }
static void Destroy ( Pointer p ) { p->~Type ( ); } };
It is wrong IMHO because: 1. The Type needs default constructor 2. The Type instance gets always created (and possibly recreated again) 3. The first Typeinstance may be "destroyed" w/o calling destructor. Alexandresu uses union aligned to fit anything with sizeof(Type): template <class T> struct CreateStatic { union MaxAlign { char t_[sizeof(T)]; short int shortInt_; int int_; long int longInt_; float float_; double double_; long double longDouble_; struct Test; int Test::* pMember_; int (Test::*pMemberFn_)(int); }; static T* Create() { static MaxAlign staticMemory_; return new(&staticMemory_) T; } static void Destroy(T* p) { p->~T(); } }; /Pavel