[odb-users] Problem with session cache and weak_ptr

[Boris Kolpackov]

Hi Marcel,

Marcel Nehring <mne at qosmotec.com> writes:

> sorry for so many questions about this topic but it is causing a lot
> of trouble and confusion here.

No problem, lazy weak pointers are tricky.


> If the object a lazy_weak_ptr points to expires, is the state of the
> pointer still loaded or will it change to unloaded?

That depends on whether the pointer pointed to the transient or
persistent objects.


> I.e. if I have a valid pointer to a persistent object, and the pointer
> expires, will loaded() return true (so that it become effectively a NULL
> pointer to a transient object) or will it return false (so that it
> effectively becomes an unloaded pointer to a persistent object)?

It will return false. Here is the "truth table" from the lazy_weak_ptr
header:

    // expired()  loaded()
    //
    //  true       true      expired pointer to transient object
    //  false      true      valid pointer to persistent object
    //  true       false     expired pointer to persistent object
    //  false      false     valid pointer to transient object
    //

Boris