SIMSCRIPT II.5 Programming Language

Modelling Concepts
Because SPEED is an attribute common to both TANKER and TUG, it is possible to use a statement
such as:
if SPEED(SHIP) is not zero
without regard to whether SHIP is a pointer to an instance of TANKER or a TUG.
When temporary entities belong to common sets or own common sets, their set pointers are, of
course, common attributes. It becomes possible to write:
for each SHIP in HARBOR.SET
with SPEED(SHIP) not zero
do
.
.
.
—so the harbor master can track all the ships steaming around in the harbor.
Under certain SIMSCRIPT II.5 implementations, it is sufficient to name common attributes and sets
in every statements, as shown. Other implementations require the use of "word numbers" as described
in the relevant user's manuals. The above declarations could be rewritten as:
every TANKER has a SPEED in word 1,
a CARGO, and belongs to the HARBOR.SET
and has a P.HARBOR.SET in word 2,
and a S.HARBOR.SET in word 3,
and a M.HARBOR.SET in word 4
every TUG has a SPEED in word 1,
and belongs to the HARBOR.SET
and has a P.HARBOR.SET in word 2,
and a S.HARBOR.SET in word 3,
and a M.HARBOR.SET in word 4
The entity structures of TANKER and TUG would look like figure 4-21.
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