complete lesson

README.md

@@ -0,0 +1,26 @@
+# Object Oriented Programming
+
+A short introduction to object oriented programming with examples in multiple languages
+
+Example Languages:
+
+- Java
+- Rust
+- C++
+- JavaScript (using TypeScript)
+
+Lessons:
+
+- [instanciating objects, accessing attributes and methods](./lessons/Instances.md)
+
+Work in progress:
+
+- creating a class
+- use attributes or functions from a function within an object
+- constructors
+- encapsulation
+- getter / setter / property
+- inheritance
+- polymorphism
+- virtual classes
+- interfaces

cpp/instances/main.cpp

@@ -2,14 +2,18 @@
 #include <cstring>
 
 int main() {
-  car a;
+  // create a new car and store it in the variable 'a'
+  car a;    
+  // set some data for that car
   a.manufacturer = "Benz";
   a.model = "Velo";
-
+    
+  // do the same for a second car
   car b;
   b.manufacturer = "Ford";
   b.model = "Model T";
 
+  // use a function of the car class to print out the information
   a.print_info();
   b.print_info();
 }

java/instances/Car.java

@@ -10,7 +10,9 @@ public class Car {
   public String model = "";
   public String manufacturer = "";
 
-  public String get_info() {
-    return "Car Information:\n- manufacturer: " + this.manufacturer + "\n- model: " + this.model;
+  public void print_info() {
+    System.out.println("Car Information:");
+    System.out.println("- manufacturer: " + this.manufacturer);
+    System.out.println("- model: " + this.model);
   }
 }

java/instances/main.java

@@ -6,13 +6,13 @@ public class main {
     a.manufacturer = "Benz";
     a.model = "Velo";
 
-    // Do the same for a second car
+    // do the same for a second car
     Car b = new Car();
     b.manufacturer = "Ford";
     b.model = "Model T";
 
     // use a function of the car class to print out the information
-    System.out.println(a.get_info());
-    System.out.println(b.get_info());
+    a.print_info();
+    b.print_info();
   }
 }

lessons/Instances.md

@@ -0,0 +1,70 @@
+# Object Instances
+
+For this short Introduction we'll only create two objects, give them some data
+and let them do their magic with one function.
+
+Objects are generally used to keep data logically grouped and also make it easy
+to perform actions on them without having to account for all the logic at the
+time of using those functions.
+
+As an example I have created a Car class. This is probably going to be the
+main class used in all further lessons, since it has a lot of room for more data
+and functions to add except for manufacturer, model and the function print_info
+in this example.
+
+```java
+/*
+ * First we create a new car and store that in a variable, here called 'a'.
+ * Usually a programming language has a keyword like 'new' to instantiate new objects.
+ * here in Java a new Object is created by Specifying variable type, variable name
+ * the keyword new and again the type that should be instantiated.
+ */
+Car a = new Car();
+
+/*
+ * To access data within an object you can use the object name followed by a dot
+ * and the name of the property.
+ * The data can be read or modified at will.
+ * Since this is just the start of working with oop,
+ * I'll also use very early cars here
+ */
+a.manufacturer = "Benz";
+a.model = "Velo";
+
+/*
+ * Then we do the same thing for a second car
+ */
+Car b = new Car();
+b.manufacturer = "Ford";
+b.model = "Model T";
+
+/*
+ * Functions can be accessed in the same way as properties, just with
+ * parentheses behind to actually run the functions.
+ * These will print out all the data we put into the objects before.
+ */
+a.print_info();
+b.print_info();
+```
+
+The above example code together with the car class will create the following output:
+
+```text
+Car Information:
+- manufacturer: Benz
+- model: Velo
+Car Information:
+- manufacturer: Ford
+- model: Model T
+```
+
+If any of the examples don't produce the same output, then congrats, you just
+got yourself the homework to fix the error and submit a pull request to this
+repository :)
+
+## Examples
+
+- [Java](../java/instances)
+- [Rust](../rust/instances)
+- [C++](../cpp/instances)
+- [JavaScript (using TypeScript)](../typescript/instances)

rust/instances/src/main.rs

@@ -2,16 +2,20 @@ mod car;
 use car::Information;
 
 fn main() {
+  // create a new car and store it in the variable 'a'
   let a = car::Car {
+    // set some data for that car
     manufacturer: "Benz".to_string(),
     model: "Velo".to_string()
   };
 
+  // do the same for a second car
   let b = car::Car {
     manufacturer: "Ford".to_string(),
     model: "Model T".to_string()
   };
 
+  // use a function of the car class to print out the information
   a.print_info();
   b.print_info();
 }

typescript/instances/index.ts

@@ -1,12 +1,16 @@
 import {Car} from './car'
 
+// create a new car and store it in the variable 'a'
 const a = new Car();
+// set some data for that car
 a.manufacturer = 'Benz';
 a.model = 'Velo';
 
+// do the same for a second car
 const b = new Car();
 b.manufacturer = 'Ford';
 b.model = 'Model T';
 
+// use a function of the car class to print out the information
 a.print_info();
 b.print_info();