Type parameters and parameterized types
Parameters
The parameters in the subprogram header are called formal parameters. They
are sometimes thought of as dummy variables because they are not variables in the usual
sense: In some cases, they are bound to storage only when the subprogram is called, and
that binding is often through some other program variables.
Subprogram call statements must include the name of the subprogram and a list of
parameters to be bound to the formal parameters of the subprogram. These parameters
are called actual parameters.
The binding of actual parameters to formal parameters is done by simple position:
The first actual parameters is bound to the first formal parameter and so forth. Such
parameters are called positional parameter.
When lists are long, however it is easy for the program writer to make mistakes in
the order of parameters in the list. One solution to this problem is to provide keyword
parameters, in which the name of formal parameter to which an actual parameter is to be
bound is specified with actual parameter. The advantage of keyword parameters is that
they can appear in any order in the actual parameter list.
SUMER(LENGTH => MY_LENGTH,
LIST => MY_ARRAY,
SUM => MY_SUM);
PAGE 4
