Singleton.md

@@ -4,7 +4,7 @@ A singleton is a class that can be **instantiated only once**: this can be very
 
 In boardcore, you can achieve this by extending the Singleton template which you can find in `src/shared/`.
 
-## Methods
+## Implementation
 The Singleton interface is a template class which exposes a single method:
 ```cpp
 inline static T* getInstance()
@@ -17,6 +17,9 @@ What this method does is:
 - If an instance of this class already exists, return that instance.
 - If an instance of this class does not exist yet, create and return a new one.
 
+> :warning: **WARNING: By definition, a Singleton is an object whose constructor is defined _private_ !**  
+> **In order to instantiate it or get a reference, the _getInstance()_ method has to be called.**
+
 ## Example
 
 From the `Singleton.h` comment:
@@ -27,7 +30,26 @@ From the `Singleton.h` comment:
  */
 class Foo : public Singleton<Foo>
 {
+    friend class Singleton<Foo>;
+
+    public:
+        void someFunction()
+        {
+            ... // do stuff
+        }
     private:
-      Foo() {} // private constructor
+        Foo() {} // PRIVATE CONSTRUCTOR
 };
 ```
+
+And in the main:
+```cpp
+int main()
+{
+    Foo* foo = Foo::getInstance();
+
+    foo->someFunction();
+
+    return 0;
+}
+```
\ No newline at end of file