Adding an example of an interface containing only a ToString method.

Author: Clément

source/code/projects/IToString/IToString/Demo.cs

@@ -0,0 +1,6 @@
+class Demo : IToString
+{
+  public string Name{get; set;}
+  public Demo(string nameP){Name = nameP;}
+  // public override string ToString(){return "The name attribute contains:" + Name;}
+}

source/code/projects/IToString/IToString/IToString.cs

@@ -0,0 +1,13 @@
+/* 
+ *  The question of adding ToString methods to interface is a bit delicate and will certainly not be on any CSCI 1302 exam. The answer is, in short: you cannot force the implementation of a ToString with an interface.
+ * This is discussed at length at                                                                                                                                                                       
+ * https://stackoverflow.com/q/510341
+ * where an alternative solution is provided (essentially: use an abstract class).
+ *
+ * Observe that this would compile just fine, even if Demo does not provide the implementation of a ToString method. Of course, Demo already posses a ToString method, the one every class inherits. 
+ */
+
+interface IToString
+{
+  string ToString();
+}

source/code/projects/IToString/IToString/Program.cs

@@ -0,0 +1,10 @@
+using System;
+
+class Program
+{
+  static void Main()
+  {
+    Demo test = new Demo("This is a test");
+    Console.WriteLine(test);
+  }
+}

source/diag/cla/FMember.txt

@@ -4,7 +4,7 @@ class Person{
     - name: string
     # nickName: string
     + commonName: string
-    + GetName(): string
+    + GetName() string
     + SetName(nameP: string)
     - NewName(newNameP)
     + Person()

source/lectures/oop/interface.md

@@ -83,6 +83,8 @@ Note that
         ```
     - there is no need for the `override` keyword,
 
+## A ToString 
+    
 ## A More Complicated Example
 
 !include diag/cla/Shape.md