AlexVegner

// If name of variable, function, class, method etc. stars with ‘_’ then it's visible only inside this file.
// Example 1:
String _str1 = 'Hello'; // private
String str2 = "World"; // public

// Example 2
void main() {
  final car = Car('Audi', 'A8');
  print('model: ${car._model}'); // visible only inside of the file
}

AlexVegner

void main() {
  dynamic value = 1;
  assert(value is int);     // True if the object has the specified type
  assert(value is! double); // False if the object has the specified type
  int intValue = value as int;
  print(intValue);
}

AlexVegner

void main() {
  String a; // null
  
  if (a == null) {
    a = 'Hello';
  }
  // equivalent to
  a ??= 'Hello';
  // equivalent to
  a = a ?? 'Hello';

AlexVegner

void main() {
  
  // *******
  // Conditional statement
  // *******
  
  
  // example: value mapping
  // '1' = 'yes'
  // '0' = 'no'

AlexVegner

//import 'package:meta/meta.dart';
  
String f1() => 'value'; // For functions that contain just one expression, you can use a shorthand syntax

String f2() {  // this function equivalent to f1
  return 'value';
}

/// Functions as first-class objects
/// You can pass a function as a parameter to another function. For example and return function

AlexVegner

/// Dart is a lexically scoped language, which means that the scope of variables is determined statically, simply by the layout of the code. You can “follow the curly braces outwards” to see if a variable is in scope.

// example
bool topLevel = true;
void main() { // 
  var insideMain = true;
  void myFunction() {
    var insideFunction = true;
    void nestedFunction() {
      var insideNestedFunction = true;

AlexVegner

import 'dart:math' as math;

class Point {
  final int x;
  final int y;
  const Point(this.x, this.y);
}

// class / abstract class can be used as mixin
class LastPoint {

AlexVegner

import 'dart:math' as math;

class MyError extends Error {}

class MyException implements Exception {
  MyException([dynamic message]);
}

void checkValue(int value) {
  switch(value) {

AlexVegner

/// class
class Pesron {
  String name; // field
  int age;

  String description() {
    // method
    return '$name, age: $age';
  }
}

AlexVegner

/// Example 1
/// Enum extension
enum NetworkState {
  unknown,
  connected,
  disconnected,
}

/// NetworkStateExtension
extension NetworkStateExt on NetworkState {