未调用std :: unique_ptr中的自定义删除器

Question

Example does not make sense but still cannot explain why custom deleter is not called.

After the answers I got, I edited my code so myP is not null before smartP goes out of scope

int * myP = NULL;

{ 
   std::unique_ptr<int, std::function<void(int*)>> smartP(myP, [](int * a) {
        *a = 8; // Custom deleter that is trying to dereference NULL never called
   }); 

   int a = 9;       
   myP = &a;

} // smartP goes out of scope, I expect custom deleter to be called

Answer 1

unique_ptr 's destructor will only call its deleter if the contained pointer is not nullptr .

From N3337, [unique.ptr.single.dtor] /2

Effects: If get() == nullptr there are no effects. Otherwise get_deleter()(get()) .