tasks a-s

Task/Polymorphism/R/polymorphism.r

@@ -0,0 +1,39 @@
+setClass("point",
+   representation(
+      x="numeric",
+      y="numeric"),
+   prototype(
+      x=0,
+      y=0))
+
+# Instantiate class with some arguments
+p1 <- new("point", x=3)
+# Access some values
+p1@x    # 3
+# Define a print method
+setMethod("print", signature("point"),
+   function(x, ...)
+   {
+      cat("This is a point, with location, (", x@x, ",", x@y, ").\n")
+   })
+print(p1)
+
+# Define a circle class
+setClass("circle",
+   representation(
+      centre="point",
+      r="numeric"),
+   prototype(
+      centre=new("point"),
+      r=1))
+circS4 <- new("circle", r=5.5)
+# Access some values
+circS4@r    # 5.5
+circS4@centre@x   # 0
+# Define a print method
+setMethod("print", signature("circle"),
+   function(x, ...)
+   {
+      cat("This is a circle, with radius", x@r, "and centre (", x@centre@x, ",", x@centre@y, ").\n")
+   })
+print(circS4)