Forbid the creation of PlainObjectBase object

Submitted by Gael Guennebaud @ggael

Assigned to Nobody

Link to original bugzilla bug (#1074)
Version: 3.3 (current stable)

Description

It is currently possible to directly create PlainObjectBase<Derived> objects, which is not very good practice as this class has been thought as an abstract base class.

So what about disabling this possibility by making all PlainObjectBase<Derived> private, and making Derived a friend class of PlainObjectBase<Derived>?

See also the following thread for some weird usages of PlainObjectBase<Derived>: https://forum.kde.org/viewtopic.php?f=74&t=128414&p=342621

Blocking

#558 (closed)