Historical errata for Dart for Hipsters

In the ajax_populate_list(container) function:

graphicNovelsTemplate(list) should be:

graphic_novels_template(list)

This causes Dart Editor to error, anyway.

The description of privacy (around page 55) is wrong. It states that super or sub-classes don’t have access to private variables.
That’s only true if they live in different libraries. Conceptually the leading “_” of any identifier is replaced by ““. Code that lives in the same library as the field (or any other variable) will thus be able to access the field. If the code comes from a different library its ”” will expand to a different name and thus make it impossible to access the field from the other library.

3.3 Booleans

In the 3 ternary expressions, like in:
greeting = name ? “Howdy $name” : “Howdy”;

the first parts are assignments, but they should be comparisons,like:
greeting == name ? …

The greeting = name ? version gives an exception:

Unhandled exception:
type ‘Null’ is not a subtype of type ‘bool’ of ‘boolean expression’.

3.5 Lists:

The statements:
muppets.some((muppet) {
return muppet.startsWith(‘C’);
});
// true

and the equivalent every and filter statement
should better be replaced with the more elegant forms:

muppets.some( (muppet) => muppet.startsWith(‘C’) ); // true
muppets.every( (muppet) => muppet.startsWith(‘C’) ); // false
muppets.filter( (muppet) => muppet.startsWith(‘C’) ); // [‘Count’]

3.6 Dates
The statement:
var mar = new Date.fromString(‘2012-03-01 Z-0500’);

gives an
Unhandled exception:
Illegal argument(s): 2012-03-01 Z-0500

fib_printer(i) {
print(“Fib($i): ” + fib(i));
}
gives no method + exception
should now be:

fib_printer(i) {
print(“Fib($i): ${fib(i)}” );
}
or even better:
fib_printer(i) => print(“Fib($i): ${fib(i)}” );

8.7 Constructors - Factory constructors

The code:
class PrettyName {
factory PrettyName(name) {
return “Pretty $name”;
}
}

does not work; it gives the following exception:

Unhandled exception:
type ‘String’ is not a subtype of type ‘PrettyName’ of ‘function result’.

10.3 Core Dart libraries

The following does not compile
(cannot find referenced source):
#import(‘html’);
#import(‘json’);

It should of course be:
#import(‘dart:html’);
#import(‘dart:json’);

10.1 # Source
In pretty_print.dart, the line:
if (thing is List) print(INDENT + Strings.join(thing, ‘, ’));
must be replaced by:
if (thing is List) print(‘$INDENT ${Strings.join(thing, ’, ‘)}’);

In the text the + method is used in various places to concatenate strings; this is no longer valid and should be replaced with string interpolations.

These are some of the occurrences:
i) code of _graphic_novels_template.dart (chapter 1)
ii) print(“Fib($i): ” + fib(i)); in § 4.1 Anonymous functions
iii) § 9.2 #import
print(“Elapsed time: ” + timer.elapsedInMs() + “ms”);
should be:
print(‘Elapsed time: ${timer.elapsedInMs()} ms’);

i)
Note: Chrome is smart enough to load #source() and #import() files only once, no
matter how many different places they might be referenced.

instead of Chrome you should mention the Dart VM

ii) in the list of libraries, dom is still mentioned
but this library is now deprecated

Map’s hasKey method does not exist, should be containsKey method, on page 14 and page 15.

eg:
if (!options.hasKey(‘age’)) {

fib(3) // => 3
should be
fib(3) // => 2

“The Set class is a List …” should be “The Set class is a Collection …”.

“The Queue is a List that can be manipulated at the beginning.” should be “The Queue is a Collection that can be manipulated at both ends.”

document.
query(‘ul#people-list’).
queryAll(‘li’).
each((li) {
li.addClass(‘highlight’);
});

should be

document.
query(‘ul#people-list’).
queryAll(‘li’).
forEach((li) {
li.classes.add(‘highlight’);
});

For create new element, Dart now support create the element directly. eg: new DivElement()

NodeList implement List. So

document.
query(‘#content’).
nodes.
append(gallery);

should be

document.
query(‘#content’).
nodes.
add(gallery);

Dart has supported method cascade. So if api doesn’t return this, it also can chainable call.

document.
query(‘blockquote’).
classes.
remove(‘subdued’);

document.
query(‘blockquote’).
classes.
add(‘highlighted’);

can write this:

document.
query(‘blockquote’).
classes..
remove(‘subdued’)..
add(‘highlighted’);

In note paragraph, dart:htmlimpl library has removed from sdk.

Dart’s new getter syntax should remove the braces. This should revise all the getter method.

For “Currently, there are no command-line switches that alter the behavior”, currently dart2js has -o/-c/-h command-line options.

For the Note paragraph, Dart now support initialization expression at the field declared. for example:

class ComicsModel {
ModelEvents on = new new ModelEvents();
}

see the article “Simplify your constructors and top-level variables” on news.dartlang.org

For the Important paragraph, about the call superclass’s constructor.

From the Dart language tour:

By default, a constructor in a subclass will call the superclass’s default constructor. If no default (zero-argument) constructor is defined in the superclass, you must manually call a constructor in the superclass.

So, in here, because ComicBook’s supercalss ComicsModel does not define a zero-argument default constructor, so ComicBook must manually call super constructor.

For test chapter.
1)Now unittest is in Dart SDK, and no need to export from svn.

two import method:
File style,#import(‘path-to-dart/pkg/unittest/unitest.dart’); or
Package style, #import(‘package:unittest/unittest.dart’);

2)In addition, dartest has removed from Dart. So DARTest and run test in browser does not work.

3)asyncTest is deprecated, it should be replaced by expectAsyncX.

4)The Expect class in dart:core is deprecated, and expect() should be used instead. eg, expect(2 + 2, equals(5));

localStorage is now implement Map, and getItem/setItem method does not exist. eg:

var json = window.localStorage.getItem(‘Comic Books’)

should be

var json = window.localStorage[‘Comic Books’]

And window.localStorage.setItem

should be

window.localStorage[‘Comic Books’] = JSON.stringify(comics);

if (comic_book[‘title’] 'Sandmn') { comic_book['title'] ‘Sandman’;
}

should be

if (comic_book[‘title’] == ‘Sandmn’) {
comic_book[‘title’] = ‘Sandman’;
}

the second == should be =

String message = “$method: ${model.url}”;
the sentence reduplicate

CanvasRenderingContext or CanvasRenderingContext2D ?

I suggest use :
CanvasRenderingContext2D context = canvas.getContext(‘2d’);

oneDay = new Duration(1)

should be

oneDay = new Duration(days:1)

Because Dart now use new named optional parameters syntax({}) and Duration now use this style, the parameter
name are not optional. See the article “BREAKING CHANGES: Duration, RegExp, Uri.fromComponents” on news.dartlang.org.

I also suggest add an introduction for named optional params and positional optional params on chapter 3.3

In the Hipster Collections section 6.2 you define the collection with the two stream controllers _onLoad and _onAdd and the models list and then go on to say that you declared only two instance variables “on” and “models”. This disconnect is repeated a few times throughout the chapter.

The first sentence has the last 2 words transposed. It reads: “JavaScript has been around for years eighteen.”

Section 10.4 Packaging with “pub”, second sentence states: “As we saw in Chapter 12, Testing Dart, on page 111, it is capable of resolving and installing dependencies”. We haven’t yet seen that chapter, and I’m not quite sure what “Testing Dart” has to do with resolving and installing dependencies.

Hello! I found issue in the code on Github first, but now I found it in the book. Please, check my PR for fixes github[dot]com/eee-c/dart-comics/pull/4.

Short description: JS can’t use Dart interpolation and script starts working before document body is loaded trying to append to document.body which is null.

Thanks!

Need to be consistent with IterableBase and Collection. See forums.pragprog.com/forums/254/topics/12488.

Starting here, but throughout the rest of the book, query() should probably be replaced with querySelector() (see groups.google.com/a/dartlang.org/forum/#!msg/misc/dJnz6DbyPbs/eDe5BwAm140J)

The discussion under DOM Ready confused me a little because I just used dart2js to make some JavaScript and through it in a normal script tag. When you do that, the rules change. I realize you recommend using the loader script, but even then the recommendation is to put the script tags at the end to avoid these issues (see www.dartlang.org/articles/embedding-in-html/). Perhaps this is a gotcha worth mentioning?

The first two paragraphs after the first code example, that begin, “We cheat in our implementation of the forEach() method…” don’t seem to have anything to do with the code shown.

The lead up to the save() code talks about how the code needs to POST on create, but PUT on update. Then the method hardcodes a POST. Oops.

The event description at the top of this page doesn’t match the actual code (on the previous page).

The text above the first code example and the actual code disagree about which interface is implemented.

The `extends IterableBase`/`implements Collection` confusion is back on this page.

This paragraph doesn’t make sense: “Back in the HipsterCollection superclass, we declare modelMaker() as abstract (by omitting the method body). create() to use this method.”

I think this sentence is in need of a verb, “It is worth pointing out that, because of how Dart manages libraries, setting HipsterSync.sync in our main.dart file, like so:”

I think the second code block should use handleException() instead of catchError(). (If not, the text above is wrong.)

Need to remove event mentions from chapter 7. They are no longer used in chapter 6.