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fix the tuple subclassing example docs

db4
Doug Coleman 2009-10-10 14:02:35 -05:00
parent 0f5c3c5d3f
commit 584cd44856
1 changed files with 5 additions and 4 deletions
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core/classes/tuple/tuple-docs.factor
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@ -129,17 +129,18 @@ ARTICLE: "tuple-inheritance-example" "Tuple subclassing example"
}
"Rectangles and parallelograms use the same algorithm for computing the area, whereas they use different algorithms for computing perimiter. Also, rectangles and parallelograms both have " { $snippet "width" } " and " { $snippet "height" } " slots. We can exploit this with subclassing:"
{ $code
"USING: math.constants math.functions ;"
"GENERIC: area ( shape -- n )"
"GENERIC: perimiter ( shape -- n )"
""
"TUPLE: shape ;"
""
"TUPLE: circle < shape radius ;"
"M: area circle radius>> sq pi * ;"
"M: perimiter circle radius>> 2 * pi * ;"
"M: circle area radius>> sq pi * ;"
"M: circle perimiter radius>> 2 * pi * ;"
""
"TUPLE: quad < shape width height"
"M: area quad [ width>> ] [ height>> ] bi * ;"
"TUPLE: quad < shape width height ;"
"M: quad area [ width>> ] [ height>> ] bi * ;"
""
"TUPLE: rectangle < quad ;"
"M: rectangle perimiter [ width>> 2 * ] [ height>> 2 * ] bi + ;"