Modified ex 3 in class delegation

Object-Oriented Programming/Class Delegation/Exercise 3/src/Task.kt

@@ -1,57 +1,46 @@
-// ClassDelegation/ClassDelegEx3.kt
 package classDelegationExercise3
 import atomictest.*
 
 interface A {
-  val x: Int
-  val z: Int
-  fun u()
-  fun v()
+  fun foo()
+  fun bar()
 }
 
 interface B {
-  val y: Int
-  val z: Int
-  fun v()
-  fun w()
+  fun foo()
+  fun baz()
 }
 
 class AA : A {
-  override val x = 1
-  override val z = 1
-  override fun u() = trace("AA.u()")
-  override fun v() = trace("AA.v()")
+  override fun foo() = trace("AA.foo()")
+  override fun bar() = trace("AA.bar()")
 }
 
 class BB : B {
-  override val y = 1
-  override val z = 1
-  override fun v() = trace("BB.v()")
-  override fun w() = trace("BB.w()")
+  override fun foo() = trace("BB.foo()")
+  override fun baz() = trace("BB.baz()")
 }
 
 class Delegation(val a: A, val b: B) :
   A by a, B by b {
-  override val z = a.z + b.z
-  override fun v() {
-    trace("Delegation.v()")
-    a.v()
-    b.v()
-    trace("Delegation.z: $z")
+  override fun foo() {
+    a.foo()
+    b.foo()
+    trace("Delegation.foo()")
   }
 }
 
 fun main() {
   val d = Delegation(AA(), BB())
-  d.u()
-  d.v()
-  d.w()
-  trace eq """
-  AA.u()
-  Delegation.v()
-  AA.v()
-  BB.v()
-  Delegation.z: 2
-  BB.w()
-  """
+  d.foo()
+  d.bar()
+  d.baz()
+  trace eq
+    """
+      AA.foo()
+      BB.foo()
+      Delegation.foo()
+      AA.bar()
+      BB.baz()
+    """
 }

Object-Oriented Programming/Class Delegation/Exercise 3/task-info.yaml

@@ -2,5 +2,24 @@ type: edu
 files:
 - name: src/Task.kt
   visible: true
+  placeholders:
+  - offset: 136
+    length: 98
+    placeholder_text: class AA
+  - offset: 236
+    length: 98
+    placeholder_text: class BB
+  - offset: 336
+    length: 140
+    placeholder_text: class Delegation
+  - offset: 491
+    length: 62
+    placeholder_text: |-
+      /*
+        val d = Delegation(AA(), BB())
+        d.foo()
+        d.bar()
+        d.baz()
+      */
 - name: test/Tests.kt
   visible: false

Object-Oriented Programming/Class Delegation/Exercise 3/task.md

@@ -1,26 +1,10 @@
 ## Class Delegation (#3)
 
 What happens when you delegate to two interfaces that have one or more
-functions or fields in common? Start with two interfaces:
+members in common? The started code contains two interfaces `A` and `B`
+that both have `foo()` member function. 
 
-```kotlin
-interface A {
-  val x: Int
-  val z: Int
-  fun u()
-  fun v()
-}
-
-interface B {
-  val y: Int
-  val z: Int
-  fun v()
-  fun w()
-}
-```
-
-Create a class `AA` that implements `A`, producing the value `1` for `x` and
-`z`, and tracing `"AA.u()"` for `u()` and `"AA.v()"` for `v()`. Create a
-similar implementation `BB` implementing `B`. Now create a class `Delegation`
-which delegates to both `A` and `B`. IntelliJ or the compiler will guide you in
-resolving the collisions.
+Create a class `AImpl` that implements `A`, that traces `"A.foo()"` for `foo()`
+and `"A.bar()"` for `bar()`. Create a similar implementation `BImpl`
+implementing `B`. Now create a class `Delegation` which delegates to both `A`
+and `B`. IntelliJ or the compiler will guide you in resolving the collisions.