guideline

Use an aggregate instead of a sequence of assignments to assign values to all components of a record.

Use an aggregate instead of a temporary variable when building a record to pass as an actual parameter.

Use positional association only when there is a conventional ordering of the arguments.

It is better to use aggregates:

Set_Position((X, Y));
Employee_Record := (Number     => 42,
                    Age        => 51,
                    Department => Software_Engineering);

than to use consecutive assignments or temporary variables:

Temporary_Position.X := 100;
Temporary_Position.Y := 200;
Set_Position(Temporary_Position);
Employee_Record.Number     := 42;
Employee_Record.Age        := 51;
Employee_Record.Department := Software_Engineering;

rationale

Using aggregates during maintenance is beneficial. If a record structure is altered, but the corresponding aggregate is not, the compiler flags the missing field in the aggregate assignment. It would not be able to detect the fact that a new assignment statement should have been added to a list of assignment statements.

Aggregates can also be a real convenience in combining data items into a record or array structure required for passing the information as a parameter. Named component association makes aggregates more readable.