classes

README.md

@@ -16,7 +16,6 @@ Lessons:
 
 Work in progress:
 
-- use attributes or functions from a function within an object
 - constructors
 - encapsulation
 - getter / setter / property

cpp/classes/README.md

@@ -0,0 +1,9 @@
+# Classes in C++
+
+In c++ classes are defined using a header file and the implementation in a
+regular .cpp file. Explanations to the structure can be found in the files themselves
+
+## Relevant files
+
+- [car.h](./car.h)
+- [car.cpp](./car.cpp)

cpp/classes/car.cpp

@@ -0,0 +1,23 @@
+// include the header file
+#include "car.h"
+
+// include necessary libraries and namespaces
+#include <iostream>
+#include <string>
+using namespace std;
+
+// define the implementation for car.print_info()
+void car::print_info()
+{
+  cout << "Car Information:" << endl;
+  // fields that are defined in the header file can just be used like normal variables here
+  cout << "- manufacturer: " << manufacturer << endl;
+  cout << "- model: " << model << endl;
+}
+
+/*
+
+That's everything for the .cpp file. 
+Since fields don't have an implementation and are already defined in the header file, they can be left out here.
+
+*/

cpp/classes/car.h

@@ -0,0 +1,40 @@
+// #pragma once is usually included in header files to make sure they are only loaded once
+// it's a simpler version of include guards, which are necessary to prevent conflicts
+#pragma once
+/*
+
+in case #pragma once is not supported by your compiler you'll need more basic include guards
+in this case it would be
+#ifndef car_h
+#define car_h
+
+...class contents
+
+#endif
+
+*/
+
+// including a necessary library and namespace to work with strings
+#include <string>
+using namespace std;
+
+// define the class
+class car
+{
+  // define the visibility of the following fields and methods
+  // in this case everything is public since visibility is a topic in future lessons
+  public:
+    // define two strings, manufacturer and model
+    std::string manufacturer;
+    std::string model;
+
+    // define a function that will print out information
+    void print_info();
+};
+
+/*
+
+That completes the header file, as you can see, there are no implementations in here.
+That's because they will be added in the car.cpp file.
+
+*/

cpp/classes/main.cpp

@@ -0,0 +1,20 @@
+#include "car.h"
+#include <cstring>
+
+int main() {
+  // create a new car and store it in the variable 'a'
+  // in contrast to java, c++ does not need initialization with the 'new' keyword here.
+  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/classes/Car.java

@@ -0,0 +1,18 @@
+/**
+ * this class is also declared with the public keyword to make it accessible
+ * outside of the current file
+ */
+public class Car {
+  public String model = "";
+  public String manufacturer = "";
+
+  public void print_info() {
+    System.out.println("Car Information:");
+    /**
+     * To access fields of the current object the this keyword is used. It is
+     * possible to omit that keyword, but it's recommended to be used anyways.
+     */
+    System.out.println("- manufacturer: " + this.manufacturer);
+    System.out.println("- model: " + this.model);
+  }
+}

java/classes/README.md

@@ -0,0 +1,5 @@
+# Java Example
+
+Relevant Files:
+
+- [Car.java](./Car.java)

java/classes/main.java

@@ -0,0 +1,18 @@
+public class main {
+  public static void main(String[] args) {
+    // create a new car and store it in the variable 'a'
+    Car a = new Car();
+    // set some data for that car
+    a.manufacturer = "Benz";
+    a.model = "Velo";
+
+    // 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
+    a.print_info();
+    b.print_info();
+  }
+}

lessons/Classes.md

@@ -1,14 +1,25 @@
 # Creating Classes
 
-This lesson is going to use the same code from last time to explain 
-the class structure itself.
+This lesson is going to use the same code from last time to explain the class
+structure itself.
 
-Since the example languages can have quite different styles of
-class declaration, I will just give a basic explanation here and then
-discuss every language in detail in their own description file.
+Since the example languages can have quite different styles of class
+declaration, I will just give a basic explanation here and then discuss every
+language in detail in their own description file.
 
-Classes are blueprints for the objects you create. You define how the
-object will look like and more importantly for the computer how much
-space it will use in memory.
+Classes are blueprints for the objects you create. You define how the object
+will look like and more importantly for the computer how much space it will use
+in memory.
 
+The main parts of a class are fields and methods. One for storing data and one
+for processing that data. Fields are placed at the top of the class and look
+like general variable declarations. Methods can take in arguments and also use
+the fields declared in the class. They can modify data in the object or just
+return some data to the caller.
 
+## Code examples and language specific explanations
+
+- [Java](../java/classes/README.md)
+- [Rust](../rust/classes/README.md)
+- [C++](../cpp/classes/README.md)
+- [JavaScript (using TypeScript)](../typescript/classes/README.md)

rust/classes/Cargo.lock

@@ -0,0 +1,5 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "rust-oop"
+version = "0.1.0"

rust/classes/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "rust-oop"
+version = "0.1.0"
+authors = ["Timo Hocker <t-hocker@web.de>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

rust/classes/README.md

@@ -0,0 +1,11 @@
+# Classes in Rust
+
+Rust doesn't have classes like Java or other typical c style languages. Instead
+there are Structs and Traits.
+
+Structs are responsible for storing data and nothing else. Traits define
+functions that can be used.
+
+## Relevant Files
+
+- [car.rs](./src/car.rs)

rust/classes/src/car.rs

@@ -0,0 +1,27 @@
+/*
+ * Define the trait Information that will contain the function print_info()
+ */
+pub trait Information {
+  // define the function, &self is an argument that will be autofilled
+  // when running the function and it will reference the current object
+  fn print_info(&self);
+}
+
+/*
+ * Define the struct Car, which will hold all the necessary information 
+ */
+pub struct Car {
+  pub manufacturer: String,
+  pub model: String
+}
+
+/*
+ * Implementing the trait Information for the struct Car
+ */
+impl Information for Car {
+  fn print_info(&self) {
+    println!("Car Information:");
+    println!("- manufacturer: {}", self.manufacturer);
+    println!("- model: {}", self.model);
+  }
+}

rust/classes/src/main.rs

@@ -0,0 +1,23 @@
+mod car;
+use car::Information;
+
+fn main() {
+  // create a new car and store it in the variable 'a'
+  // rust also doesn't use the 'new' keyword
+  // all attributes have to be defined upon creation of the object
+  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/classes/README.md

@@ -0,0 +1,5 @@
+# Typescript Example
+
+## Relevant Files
+
+- [car.ts](./car.ts)

typescript/classes/car.ts

@@ -0,0 +1,15 @@
+/**
+ * the class is defined with the export keyword to make it usable outside of the current file
+ */
+export class Car {
+  // define the fields
+  manufacturer: string = '';
+  model: string = '';
+
+  // define the function print_info
+  print_info() {
+    console.log('Car Information:');
+    console.log(`- manufacturer: ${this.manufacturer}`);
+    console.log(`- model: ${this.model}`);
+  }
+}

typescript/classes/index.ts

@@ -0,0 +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();

typescript/classes/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "ts-oop",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC"
+}

typescript/classes/tsconfig.json

@@ -0,0 +1,66 @@
+{
+  "compilerOptions": {
+    /* Basic Options */
+    // "incremental": true,                   /* Enable incremental compilation */
+    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
+    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
+    // "lib": [],                             /* Specify library files to be included in the compilation. */
+    // "allowJs": true,                       /* Allow javascript files to be compiled. */
+    // "checkJs": true,                       /* Report errors in .js files. */
+    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
+    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
+    // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
+    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
+    // "outFile": "./dist",                       /* Concatenate and emit output to single file. */
+    "outDir": "./dist",                        /* Redirect output structure to the directory. */
+    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
+    // "composite": true,                     /* Enable project compilation */
+    // "tsBuildInfoFile": "./",               /* Specify file to store incremental compilation information */
+    // "removeComments": true,                /* Do not emit comments to output. */
+    // "noEmit": true,                        /* Do not emit outputs. */
+    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
+    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
+    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
+
+    /* Strict Type-Checking Options */
+    "strict": true,                           /* Enable all strict type-checking options. */
+    // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
+    // "strictNullChecks": true,              /* Enable strict null checks. */
+    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
+    // "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
+    // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
+    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
+    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
+
+    /* Additional Checks */
+    // "noUnusedLocals": true,                /* Report errors on unused locals. */
+    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
+    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
+    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
+
+    /* Module Resolution Options */
+    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
+    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
+    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
+    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
+    // "typeRoots": [],                       /* List of folders to include type definitions from. */
+    // "types": [],                           /* Type declaration files to be included in compilation. */
+    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
+    "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
+    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "allowUmdGlobalAccess": true,          /* Allow accessing UMD globals from modules. */
+
+    /* Source Map Options */
+    // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */
+    // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. */
+    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
+    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
+
+    /* Experimental Options */
+    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
+    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
+
+    /* Advanced Options */
+    "forceConsistentCasingInFileNames": true  /* Disallow inconsistently-cased references to the same file. */
+  }
+}