Dart

Links

• DartAsynchron
• https://codingwithjoe.com/dart-fundamentals-async-await
• https://dartpad.dev

Statements

for (var ix in list) {}
for (int ix = 0; ix < 10; ix++) {}
while (doIt()){ }

Class

abstract class BaseLogger {
  int _errors = 0;
  void BaseLogger(){
  }
  // abstract function:
  void log(string message);
  void error(string message){
    _errors++;
    log('+++ ' + message);
  }
class Logger extends BaseLogger {
}
...
  var logger = Logger('std.log');

Interface

• Jede Klasse kann Interface sein. Dann muss jede Methode überschrieben werden

class D implements A, B, C {
  @override
  void doIt(){
    // ...
  }
}

DateTime

var date = new DateTime.now();

String

Formatierung

import 'package:sprintf/sprintf.dart';
sprintf("%02d %s", [1, "Hi"]);
print("${new DateTime.now().toString()}: $message\n");

Besonderheiten

• entweder optionale Positionsparameter oder optionale Namensparameter, nicht beide.

String substr(String str, int pos, [int length, bool uppercase]){ ... }
<pre>String substr2(String str, int pos, {int length, bool uppercase, Logger logger}){ ... }
x = substr('Hi world', 3, 2);
y = substr2('Hi world', 3, length:2, logger:logger);

• ..-Operator: Mehrfachzugriff auf voriges Objekt:

var person = Person()..name='Joe'..id=25;
var p = Point(10, -12)..setColor(green)..setWeight(1.22);