Variable scope, libraries

My explanation was wrong, I use an array of course.

I wasn't talking about an array of pointers to dynamically allocated objects. I was talking about an array of objects. Forgo the dynamic allocation entirely. On platforms with such limited memory footprints, dynamic allocation is rarely of any true benefit.

Is there a precise documentation somewhere?

Variable scope on the Arduino is the same as any standard C/C++ environment. There are no differences for an Arduino.