new tasks

Task/Deepcopy/Go/deepcopy-2.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+    "encoding/gob"
+    "fmt"
+    "os"
+)
+
+// capability requested by task
+func deepcopy(dst, src interface{}) error {
+    r, w, err := os.Pipe()
+    if err != nil {
+        return err
+    }
+    enc := gob.NewEncoder(w)
+    err = enc.Encode(src)
+    if err != nil {
+        return err
+    }
+    dec := gob.NewDecoder(r)
+    return dec.Decode(dst)
+}
+
+// define linked list type, an example of a recursive type
+type link struct {
+    Value string
+    Next  *link
+}
+
+// method satisfies stringer interface for fmt.Println
+func (l *link) String() string {
+    if l == nil {
+        return "nil"
+    }
+    s := "(" + l.Value
+    for l = l.Next; l != nil; l = l.Next {
+        s += " " + l.Value
+    }
+    return s + ")"
+}
+
+func main() {
+    // create a linked list with two elements
+    l1 := &link{"a", &link{Value: "b"}}
+    // print original
+    fmt.Println(l1)
+    // declare a variable to hold deep copy
+    var l2 *link
+    // copy
+    if err := deepcopy(&l2, l1); err != nil {
+        fmt.Println(err)
+        return
+    }
+    // print copy
+    fmt.Println(l2)
+    // now change contents of original list
+    l1.Value, l1.Next.Value = "c", "d"
+    // show that it is changed
+    fmt.Println(l1)
+    // show that copy is unaffected
+    fmt.Println(l2)
+}