6 Subprograms
A
subprogram is a program unit or intrinsic operation whose execution is
invoked by a subprogram call. There are two forms of subprogram: procedures
and functions. A procedure call is a
statement;
a function call is an expression and returns a value. The definition
of a subprogram can be given in two parts: a subprogram declaration defining
its interface, and a
subprogram_body
defining its execution. [Operators and enumeration literals are functions.]
To be honest: A function call is an expression,
but more specifically it is a
name.
Term entry: subprogram —
unit of a program that can be brought into execution in various contexts,
with the invocation being a subprogram call that can parameterize the
effect of the subprogram through the passing of operands
Note: There are two forms of subprograms: functions, which return values,
and procedures, which do not.
Term entry: function — form
of subprogram that returns a result and can be called as part of an expression
Term entry: procedure —
form of subprogram that does not return a result and can only be invoked
by a statement
{
AI05-0299-1}
A
callable entity is a subprogram or entry
(see Section 9).
A callable entity is invoked by
a
call; that is, a subprogram call or entry call.
A
callable construct is a construct that defines the action of a
call upon a callable entity: a
subprogram_body,
entry_body,
or
accept_statement.
Ramification: Note that “callable
entity” includes predefined operators, enumeration literals, and
abstract subprograms. “Call” includes calls of these things.
They do not have callable constructs, since they don't have completions.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe
