Just using a standard std::list<> to hold plugins is problematic, because
we want to push Plugins to the list from within each Plugin's constructor
that is executed during static initialization. Since the order of static
initialization is undefined in C++, it may happen that a Plugin
constructor is executed before the list could be initialized. Therefore,
we use the Nifty Counter Idiom [1] to initialize the list ourself before
the first usage.
In short:
- allocate a buffer for the list
- initialize list before first usage
- (complicatedly) declaring a buffer is neccessary in order to avoid
that the constructor of the static list is executed again
