timsneath

import 'dart:async';
import 'dart:math' show Random;

main() async {
  print('Compute π using the Monte Carlo method.');
  await for (final estimate in computePi().take(100)) {
    print('π ≅ $estimate');
  }
}
/// Generates a stream of increasingly accurate estimates of π.

timsneath

// In null-safe Dart, none of these can ever be null.
var widget = Text('Hello');
final status = GetStatus();
String m = '';

timsneath

void honk(int? loudness) {
  if (loudness == null) {
    // No loudness specified, notify the developer
    // with maximum loudness.
    _playSound('error.wav', volume: 11);
    return;
  }
  // Loudness is non-null, let's just clamp it to acceptable levels.
  _playSound('honk.wav', volume: loudness.clamp(0, 11));
}

timsneath

class StatusLine extends StatelessWidget {
  final Status status;
  StatusLine({this.status: Status.failed});
  @override
  Widget build(BuildContext context) {
    // This local variable is non-nullable, but not initialized.
    String statusText;
    if (status == Status.ok) {
      statusText = 'Update succeeded';
    } else {

timsneath

// These are all nullable variables.
Text? t = Text('Hello');  // Can be null later.
final Status? s = getStatus();  // Maybe the function returns null.
String? n;  // Is null at first. Can be null at any later time, too.

timsneath

// In function parameters.
void initialize(int? count) {
  // It's possible that count is null.
}
// In function return values.
static List<double?>? getTemperatures() {
  // Can return null instead of a List, and the list can contain nulls.
}

timsneath

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // Get data from services. Note: in a real application,
    // these would be async calls, but we're using sync calls
    // for simplicity.
    final localizedAppName = Config.getAppName();
    final temperatures = WeatherService.getTemperatures();
    return MaterialApp(
      home: Scaffold(

timsneath

import 'package:filepicker_windows/filepicker_windows.dart';

void main() {
  final file = OpenFilePicker()
    ..filterSpecification = {
      'Word Document (*.doc)': '*.doc',
      'Web Page (*.htm; *.html)': '*.htm;*.html',
      'Text Document (*.txt)': '*.txt',
      'All Files': '*.*'
    }

timsneath

import 'dart:ffi';
import 'package:ffi/ffi.dart';

// more imports

import 'IModalWindow.dart';

/// @nodoc
const IID_IFileDialog = '{42f85136-db7e-439c-85f1-e4075d135fc8}';

timsneath

#include "windows.h"
#include "Shobjidl.h"

// vtable_start 4
MIDL_INTERFACE("42f85136-db7e-439c-85f1-e4075d135fc8")
IFileDialog : public IModalWindow
{
public:
    virtual HRESULT STDMETHODCALLTYPE SetFileTypes( 
        /* [in] */ UINT cFileTypes,