tomaszpolanski

import 'dart:math' as math;

import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';

class SliverFloatingHeader extends SingleChildRenderObjectWidget {
  const SliverFloatingHeader({
    Key key,
    Widget child,
  }) : super(key: key, child: child);

tomaszpolanski

# Check https://dart-lang.github.io/linter/lints/ for lint rules documentation
# Update from http://dart-lang.github.io/linter/lints/options/options.html

analyzer:
  errors:
    missing_required_param: error
    missing_return: error
    todo: ignore
  language:
    strict-inference: true

tomaszpolanski

import 'package:flutter/material.dart';

void main() {
  // Displays build timeline
  debugProfileBuildsEnabled = true;
  runApp(GlobalKeyWidget());
}


class WidgetsWithKeysAreJustUpdated extends StatefulWidget {

tomaszpolanski

package com.tomek

abstract class Animal(val size: Int)

class Dog(val cuteness: Int): Animal(100)

class Spider(val terrorFactor: Int): Animal(1)


// Covariance

tomaszpolanski

╔══════════╦═════════════════╦═══════════════╦═══════════════╗
║ Function ║ Receiver (this) ║ Argument (it) ║    Result     ║
╠══════════╬═════════════════╬═══════════════╬═══════════════╣
║ let      ║ this@MyClass    ║ String("...") ║ Int(42)       ║
║ run      ║ String("...")   ║ N\A           ║ Int(42)       ║
║ run*     ║ this@MyClass    ║ N\A           ║ Int(42)       ║
║ with*    ║ String("...")   ║ N\A           ║ Int(42)       ║
║ apply    ║ String("...")   ║ N\A           ║ String("...") ║
║ also     ║ this@MyClass    ║ String("...") ║ String("...") ║
╚══════════╩═════════════════╩═══════════════╩═══════════════╝

tomaszpolanski

import android.annotation.SuppressLint
import android.os.Parcelable
import kotlinx.android.parcel.Parcelize

@SuppressLint("ParcelCreator") // IntelliJ Issue https://youtrack.jetbrains.com/issue/KT-19300
@Parcelize
data class Movie(val title: String) : Parcelable

tomaszpolanski

final String? text;

@override
Widget build(BuildContext context) {
  final _text = text; // Assign field to local final variable
  return Column(
    children: [
      if (_text != null) Text(_text), // The `!` is not longer needed
    ],
  );

tomaszpolanski

void main() {
  final A example = B();
  if (example.text != null) {
    print(example.text!.length); // Throws null reference exception
  }
}

tomaszpolanski

class A {
  A(this.text);

  final String? text; // Final field
}

class B implements A {
  bool _first = true;

  @override

tomaszpolanski

final String? text;

@override
Widget build(BuildContext context) {
  return Column(
    children: [
      if (text != null) Text(text!), // Won't compile without `!` in `text!` 
    ],
  );
}