c++cpp-core-guidelinesguideline-support-library

Is gsl::owner usable for shared-ownership?

For example, can it be used in Qt for the following?

gsl::owner<QWidget*> w{new QWidget{parent}}

In this example, the ownership is shared by the new-site and the parent, because the code who has new-ed the object can delete w, and W's destructor will take itself out of parent children list. However, if w is not deleted at the new-site, then parent will delete it in its destructor.

  1. Is this an example of shared ownership, and
  2. can gsl::owner be used for it?
Solution

  • Is this an example of shared ownership

    No, you have two places claiming unique ownership.

    can gsl::owner be used for it

    If w can outlive the object pointed to by parent, then it might become invalid, leading to undefined behaviour.

    If you want a pointer type that interfaces with Qt's parent-child ownership, use QPointer