Un linguaggio intuitivo e familiare ed un vasto insieme di librerie e strumenti di sviluppo: questo è Dart, la nuova piattaforma "batteries included" orientata allo sviluppo di web application scalabili e compatibili con i maggiori browser moderni, desktop e mobile, sviluppata in Google. Al Codemotion Milano 2014 vedremo una panoramica del linguaggio e svilupperemo insieme una web app di esempio per vedere più da vicino tutti i vantaggi di Dart rispetto alle piattaforme tradizionali.

1. MILAN november 28th/29th 2014
Giovanni Laquidara
Join the Dart Side of Web Development.
glaquidara@gmail.com - Google Developer Group Roma

2. MILAN november 28th/29th 2014 – Speaker's name
dest templates
Backbone Marionette
Modernizr
Backbone
require.js
jQuery
moment.js
PhantomJS
Jasmine
Docs
Docs
Docs
Docs
Docs
Docs
Docs
Docs
Docs

3. MILAN november 28th/29th 2014 – Speaker's name
● Language
● Libraries
● Tools
● Compilation to Javascript

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Dart is open source
● BSD-style license
● dart.googlecode.com
● GitHub mirror
● Contributing guide
● ECMA Standard (TC52)
● Production ready (1.8)

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Compile to JavaScript, runs across the modern web

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Run Dart on
the server with
the Dart VM

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import 'dart:math' show Random; // Import a class from a library.
void main() { // The app starts executing here.
print(new Dice(n: 12).roll()); // Print a new object's value.
}
class Dice { // Define a class.
static Random shaker = new Random(); // Define a class variable.
int sides, value; // Define instance variables.
String toString() => '$value'; // Define a method using shorthand
syntax.
Dice({int n: 6}) { // Define a constructor.
if (4 <= n && n <= 20) {
sides = n;
} else {
throw new ArgumentError(/* */); // Support for errors and exceptions.
}
}
int roll() { // Define an instance method.
return value = shaker.nextInt(sides) + 1; // Get a random number.
}
}

8. MILAN november 28th/29th 2014 class H –u Spgeak er's{ name
num strength;
}

9. MILAN november 28th/29th 2014 class H –u Spgeak er's{ name
num _strength;
num get strength {
// some code
return this._strength;
}
set strength(num value) {
// do something with value;
this._strength = value;
}
}

10. MILAN november 28th/29th 2014 class H –u Spgeak er's{ name
num _strength;
Hug(strength) {
this._strength = strength;
}
Hug.light(strength) {
this._strength = 0;
}
}

11. MILAN november 28th/29th 2014 class H –u Spgeak er's{ name
num _strength;
Hug(this._strength);
}

12. MILAN november 28th/29th 2014 class H –u Spgeak er's{ name
num _strength;
Hug(this._strength);
Hug operator +(Hug other) {
return new Hug(strength +
other.strength);
}
}

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var button = new ButtonElement();
button.id = 'fancy';
button.text = 'Click Point';
button.classes.add('important');
button.onClick.listen((e) => addTopHat());
parentElement.children.add(button);

14. MILAN november 28th/29th 2014 – Speaker's name
var button = new ButtonElement();
..id = 'fancy';
..text = 'Click Point';
..classes.add(‘important');
..onClick.listen((e) => addTopHat());
parentElement.children.add(button);

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Missing getter?
"Coffee".missing // ??
Class 'String' has no instance getter 'missing'.
NoSuchMethodError : method not found: 'missing' Receiver:
"Coffee"
Arguments: []

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String compared to
number?
“2” > 1 // ??
Unhandled exception:
Class 'String' has no instance method '>'.
NoSuchMethodError : method not found: '>'
Receiver: "2"
Arguments: [1]

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Lexical Closures?
var talk = (s) => print(s);
talk("Hi there");

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void main() {
String name = "Giovanni Laquidara";
print(initials(name));
}
String initials(String name) {
StringBuffer retValue = new StringBuffer();
name.split(" ").forEach( (String part ) {
retValue.write(part[0] + '.');
});
return retValue.toString();
}

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main() {
var name = "Giovanni Laquidara";
print(initials(name));
}
initials(name) {
var retValue = new StringBuffer();
name.split(" ").forEach( ( part ) {
retValue.write(part[0] + '.');
});
return retValue.toString();
}

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import 'dart:html';
InputElement toDoInput;
UListElement toDoList;
void main() {
toDoInput = querySelector("#to-do-input");
toDoList = querySelector("#to-do-list");
toDoInput.onChange.listen(addToDoItem);
}
void addToDoItem(Event event) {
LIElement newToDo = new LIElement();
newToDo.text = toDoInput.value;
toDoInput.value = '';
toDoList.children.add(newToDo);
}

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import 'dart:async' show Future, Completer;
void main() {
loadNews().then( (news) {
//Do something with news
});
print("Just print!");
}
Future loadNews() {
Completer completer = new Completer();
//Insert very slow process here
completer.complete();
return completer.future;
}

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import 'dart:io';
main() {
HttpServer.bind(InternetAddress.LOOPBACK_IP_V4, 4040)
.then((HttpServer server) {
print('listening on localhost, port $
{server.port}');
server.listen((HttpRequest request) {
request.response.write('Hello, world!');
request.response.close();
});
}).catchError((e) => print(e.toString()));
}

23. MILAN november 28th/29th 2014 – Speaker's name
Use the tools you already know

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Pub
+1500 Packages
https://pub.dartlang.org/

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pubspec.yaml
name: gdghunt
description: A application using google play game services
version: 0.1.0
author: Giovanni Laquidara
dependencies:
googleapis: any
googleapis_auth: any
browser: any
core_elements: ">=0.2.0 <0.3.0"
polymer: ">=0.12.0 <0.13.0"
paper_elements: ">=0.1.0 <0.2.0"

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The web is full of links, yet web dev has no linker
imports
main Library
calls
foo bar boo
baz
Tree shaking
dart2js
main foo bar

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(bigger is better)
https://www.dartlang.org/performance

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https://www.dartlang.org/cloud/

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http://goo.gl/xpFhgY

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32. MILAN november 28th/29th 2014 – Speaker's name
Designed for Dart: use classes, annotations, and more. Build apps that scale.
AngularDart brings the proven Angular philosophy of testable, succinct web development to Dart.
AngularDart embraces modern web platform features, starting with Shadow DOM and Web Components.

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Polymer
https://www.dartlang.org/polymer/

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And Games?

35. MILAN november 28th/29th 2014 – Speaker's name

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Homepage: https://dartlang.org
API Reference: https://api.dartlang.org
Pub Packages: https://pub.dartlang.org

37. MILAN november 28th/29th 2014 – Speaker's name
Giovanni Laquidara
+GiovanniLaquidara
@joaolaq
joaobiriba
http://roma.gdg.io/
thanks() => new FeedBack();
getQuestions().then( (what) {
answer(what);
});