std :: list.remove正在调用析构函数，但不会删除它

Question

I am having a problem with std::list.

std::list<Component*> mComponents;
//add some pointer in it
Component * comp = getComponent("positionComponent");
mComponents.remove(comp);

For some reason, it calls the destructor of the comp pointer but doesn't delete it; items that are removed through destructor gets removed, while all the other items in the list kept intact. What can cause this behavior?

Answer 1

Calling list.remove does call the destructor of the contained type, but in your case, the destructor for Component * is being called, which is a no-op. You must manually find the item and delete it before removing it.

auto item = std::find(mComponents.begin(), mComponents.end(), comp);
if(item != mComponents.end()) {
  delete *item;
  mComponents.remove(item);
}

This is the reason why it is not advisable to stick raw pointers in standard containers. You should use std::list<std::unique_ptr<Component>> instead. The unique_ptr will call delete on the managed object for you.

Or if you're using a pre-C++11 compiler, boost::ptr_list is another option.