1/2
A null_procedure_declaration provides a shorthand to declare a procedure with an empty body.
2/2
null_procedure_declaration::=
[overriding_indicator]
procedure_specification is null;
3/2
A null_procedure_declaration declares a null procedure.A completion is not allowed for a null_procedure_declaration.
4/2
The execution of a null procedure is invoked by a subprogram call. For the execution of a subprogram call on a null procedure, the execution of the subprogram_body has no effect.
5/2
The elaboration of a null_procedure_declaration has no effect.
6/2
procedure Simplify(Expr : in out Expression) is null; −− see 3.9 −− By default, Simplify does nothing, but it may be overridden in extensions of Expression