SIMSCRIPT II.5 Programming Language

Advanced Topics
Program 6-2.
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preamble
temporary entities
every JOB has a VALUE, a RANKING.FUNCTION, owns a
ROUTING, and belongs to a QUEUE
every PATH has an ORIGIN, a DESTINATION, a DISTANCE,
and belongs to a ROUTING
permanent entities
every MACHINE owns a QUEUE
define QUEUE as a set ranked by high RANKING
define ROUTING as a set ranked by low DISTANCE
define RANKING as an integer function
end
routine RANKING(J)
define J as an integer variable
return with ORIGIN(F.ROUTING(J))
end
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6.8 Using “Optional” Attributes
In certain situations involving the processing of large amounts of data, the programmer may need
to define entities with a large number of attributes, many of which, however, are constant. For example,
in census data records the code n/a (not applicable) may appear in several places. When it
is desired to conserve the amount of space allocated to individual entity records, function attributes
may be used to define "optional attributes." These are actually represented by entities stored in a
special set only if their values differ from specified default values. Thus, in the following example,
if the optional attribute RAPID.TRANSIT is other than zero for a particular city, a record for it will
appear in that city's optional attribute set. Otherwise, the value of RAPID.TRANSIT would be found
in the default list (DEFAULT(1)=0).
The following declarations and programs show how to set up and use optional attributes.
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