6.7 Null Procedures
Reason: There are no null functions because
the return value has to be constructed somehow; a function that always
raises Program_Error doesn't seem very useful or worth the complication.
Ramification: Thus, a null procedure
is equivalent to the body
with the exception that a null procedure can
be used in place of a procedure specification.
Example of the declaration of a null procedure:
Simplify(Expr : in out
Expression) is null
; -- see 3.9
-- By default, Simplify does nothing, but it can may be overridden in extensions of Expression
Extensions to Ada 95
Extensions to Ada 2005
Wording Changes from Ada 2012
Clarified the term “null procedure”
so it matches the meaning expected in 6.1.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe