94 lines
2.6 KiB
Plaintext
94 lines
2.6 KiB
Plaintext
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/************************************************************************/
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/* */
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/* Now some examples of using the above definitions ... */
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/* */
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/************************************************************************/
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run :-
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banner,
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points,
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ellipse,
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lines,
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circle.
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setup_points(P45, P66, AnotherP45, Pm4m3, P00) :-
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P45 = point(4, 5),
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P66 = point(6, 6),
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AnotherP45 = P45,
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Pm4m3 = point(-4, -3),
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P00 = point(0, 0).
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setup_lines(L1, L2, L3, L4) :-
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setup_points(P45, P66, _, Pm4m3, P00),
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L1 = line(P00, P45),
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L2 = line(Pm4m3, P66),
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L3 = line(Pm4m3, P45),
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L4 = line(P00, P66).
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banner :-
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write('Logtalk adaptation of a Ben Staveley-Taylor POEM example.'), nl,
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write('Original banner:'), nl, nl,
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nl,
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write('POEM demonstration file.'), nl, nl,
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write('The example output that follows is produced by Prolog code'), nl,
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write('using the object language enhancement POEM. Please look'), nl,
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write('through the code file "shapes.pl" provided to understand how'), nl,
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write('the class facilities are being used.'), nl.
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points :-
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nl,
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write('(1) point manipulation:'), nl,
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setup_points(P45, P66, AnotherP45, _, P00),
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write('distance from (4,5) to (6,6) is '),
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P45::distance(P66, D),
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write(D), nl,
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P45::identical(AnotherP45),
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write('P45 and AnotherP45 are identical points'), nl,
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\+ P00::identical(P66),
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write('P00 and P66 are different points'), nl.
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ellipse :-
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nl,
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write('(2) ellipse manipulation:'), nl,
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P56 = point(5, 6),
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E = ellipse(P56, 3, 5),
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write('Area of ellipse of semi-axes 3 and 5 is '),
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E::area(A),
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write(A), nl.
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lines :-
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nl,
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write('(3) line manipulation:'), nl,
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setup_lines( L1, L2, L3, L4 ),
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P33 = point(3, 3),
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write('distance from '),write(L2),write(' to '),write(P33),write(' is '),
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L2::distance(P33, D),
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write(D), nl,
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L1::intersects(L2),
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write(L1), write(' intesects '), write(L2), nl,
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\+ L3::intersects(L4),
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write(L3), write(' does not intersect '), write(L4), nl.
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circle :-
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nl,
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write('(4) circle manipulation:'), nl,
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write(' Circles are subsets of ellipses, so the "area" function'), nl,
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write(' is available, and a new "circumference" function.'), nl,
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P22 = point(2, 2),
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C = circle(P22, 3),
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write('Area of circle radius 3 is '),
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C::area(A),
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write(A), nl,
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write('Circumference of circle radius 3 is '),
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C::circumference(Circ),
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write(Circ), nl, nl.
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