5. Genericity

Ada is one of the first languages to implement genericity, seen here as a sophisticated macro-expansion mechanism with typing control. Any program unit (function, procedure, package) can be generic, and a generic unit can itself include another generic unit.

A generic unit is described by generic types, which are specified when instantiated into an actual unit. And it can be used as if it had been programmed "normally".

Formal generic parameters can be :

• a variable (parameter in in out mode) or a constant (parameter in in mode) ;

• a type for which it is possible to specify a form: enumerated type, integer, decimal, array, with or without discriminant, and even private or limited private. These assumptions determine the operations that can be used within the...