Dart Templates

As mentioned by Seth Ladd, Dart now has a template system in the bleeding_edge branch. One way to learn what is offered, is to look at the uitest.dart unit test. Since the template code is in flux I’ve created some scripts to help init and build templates. A sample Dart Template Example is provided to follow along with this post. Please keep in mind this is currently subject to change by the Dart team, provide feedback to help the project along.

exportTemplateUtils.sh script is used for exporting all the dependent code from the dartlang code base. The template build script depends on lib, css, and template folders from the utils directory.

$ ./exportTemplateUtils.sh 
A    lib
Exported revision 5635.
A    css
Exported revision 5635.
A    template
Exported revision 5635.

The DivisionSales.tmpl was ripped from the unit test and adjusted for the project. The template keyword is used for defining the template name. Inside the template you can have css, html and scripting. Dart team is currently experimenting with the following.

template DivisionSales(var divisions) {
  css {
    .division-item {
      background-color: #bbb;
      border-top: 2px solid white;
      line-height: 20pt;
      padding-left: 5px;
    .product-item {
      background-color: lightgray;
      margin-left: 10px;
      border-top: 2px solid white;
      line-height: 20pt;
    .product-title {
      position: absolute;
      left: 45px;
    .product-name {
      font-weight: bold;
      position: absolute;
      left: 100px;
    .product-users {
      position: absolute;
      right: 150px;
      font-style: italic;
      color: gray;
      width: 110px;
    .expand-collapse {
      margin-left: 5px;
      margin-right: 5px;
      vertical-align: top;
      cursor: pointer;
    .expand {
      font-size: 9pt;
    .collapse {
      font-size: 8pt;
    .show-sales {
      display: inherit;
    .hide-sales {
      display: none;
    .sales-item {
      font-family: arial;
      background-color: lightgray;
      margin-left: 10px;
      border-top: 1px solid white;
      line-height: 18pt;
      padding-left: 5px;
    .ytd-sales {
      position: absolute;
      left: 100px;
    ${#each divisions}
      <div class="division-item">
        ${#each divisions.products}
          <div class="product-item">
            <span var=productZippy class="expand-collapse expand">▼</span>
            <span class='product-title'>Product</span>
            <span class="product-name">${name}</span>
            <span class="product-users">${users}&nbsp;</span> 
            <div class="show-sales">
              ${#each products.sales}
                <div class="sales-item">
                  <span class="ytd-sales">${yearly}</span>

template Header(String company, Date date) {
  css {
    .header {
      background-color: slateGray;
      font-family: arial;
      color: lightgray;
      font-weight: bold;
      padding-top: 20px;
  <div class='header' align=center>
    <div align=right>${date}</div>

The scripting is very basic at the moment. Looking at the tokenkind.dart one can get an idea of what is supported.

  // Synthesized tokens:

  static final int END_NO_SCOPE_TAG = 50;       // />
  static final int START_EXPRESSION = 51;       // ${
  static final int START_COMMAND = 52;          // ${#
  static final int END_COMMAND = 53;            // ${/
  static final int EACH_COMMAND = 53;           // ${#each list}
  static final int WITH_COMMAND = 54;           // ${#with object}
  static final int IF_COMMAND = 55;             // ${#if (expression)}
  static final int ELSE_COMMAND = 56;           // ${#else}

buildTemplates.sh script will loop over all *.tmpl files in the current working directory and generate *.dart files for each one.

$ ./buildTemplates.sh 

Building dart templates

Parsed /Users/adam/dart/DartTemplateExample/DivisionSales.tmpl in 3134 msec.
Codegen /Users/adam/dart/DartTemplateExample/DivisionSales.tmpl in 215 msec.
Wrote file /Users/adam/dart/DartTemplateExample/DivisionSales.dart in 215 msec.

Copy & Paste import statements


After the dart code is generated the following source statements can be copied into the main/lib.


class Sales {
  String country;
  String yearly;
  Sales(this.country, this.yearly);

class Products {
  List<Sales> sales;
  String name;
  String users;
  Products(this.name, this.users, this.sales);

class Divisions {
  List<Products> products;
  String id;
  String name;
  Divisions(this.id, this.name, this.products);

class DartTemplateExample {

  DartTemplateExample() {

  void run() {
    document.body.elements.add(new Header("Dollar Shave Club", new Date.now().toString()).root);
    List<Sales> sales = [new Sales("USA", "3500"), new Sales("USA", "4500")];
    List<Products> products = [new Products("Razor", "Sammy", sales)];
    List<Divisions> divisions = [new Divisions("South West", "A-Team", products), new Divisions("North East", "B-Team", products),];
    DivisionSales divisionSales = new DivisionSales(divisions);

void main() {
  new DartTemplateExample().run();

This example is deployed on github. You can also experiment with the template system to see what code gets generated on a live page. At first glance the template system is simple enough to use, I would assume things would change in the future. For now the Dart team has provided enough for people to start banging away and provide feedback.


Dart classify markup example

I was looking for a simple way to create some markup dynamically of syntax highlighted dart code, in dart! A big thanks to Bob Nystrom from the Dart team for suggesting the simplest solution. Use classify from dartdoc.

A live example of this can be found here along with the source code.

Example of how to use dartdoc/classify.dart
dartdoc is used for generating static HTML for the api.dartlang.org site. This example shows how importing dartdoc/classify.dart one could generate syntax highlighted dart code at runtime.

Currently you need to modify the import statement to reference the location of classify.dart.

#import('../../dart_bleeding/dart/utils/dartdoc/classify.dart', prefix:"classify");

Build with minfrog for best results. At the moment dart editor does not seem happy with me on importing dartdoc/classify.dart. So compiling with minfrog worked best.

minfrog --compile-only --out=ClassifyExample.dart.js ClassifyExample.dart

Using classify
This is the easiest part! Create a SourceFile and add pass it along to classifySource which will return a properly formatted string of span elements that has class attributes set. From that point you can add a css style to the span elements.

    String code = "main() { print('hello world'); }";
    classify.SourceFile sf = new classify.SourceFile("sf.dart", code);
    String c = classify.classifySource(sf);
   <span class="i ">main</span><span class="p ">(</span><span class="p ">)</span><span> 
   </span><span class="p ">{</span><span> </span><span class="i ">print</span>
   <span class="p ">(</span><span class="s si">'hello world'</span>
   <span class="p ">)</span><span class="p ">;</span><span> </span><span class="p ">}</span> 

Example css style

/* Syntax highlighting. */
/* Note: these correspond to the constants in classify.dart. */
.e { color: hsl(  0, 100%, 70%); } /* Error */
.c { color: hsl(220,  20%, 65%); } /* Comment */
.i { color: hsl(220,  20%, 20%); } /* Identifier */
.k { color: hsl(220, 100%, 50%); } /* Keyword */
.p { color: hsl(220,  20%, 50%); } /* Punctuation */
.o { color: hsl(220,  40%, 50%); } /* Operator */
.s { color: hsl( 40,  90%, 40%); } /* String */
.n { color: hsl( 30,  70%, 50%); } /* Number */
.t { color: hsl(180,  40%, 40%); } /* Type Name */
.r { color: hsl(200, 100%, 50%); } /* Special Identifier */
.a { color: hsl(220, 100%, 45%); } /* Arrow */

/* Interpolated expressions within strings. */
.si {
  background: hsl(40, 100%, 90%);

.s.si { background: hsl(40, 80%, 95%); }
.i.si { color: hsl(40, 30%, 30%); }
.p.si { color: hsl(40, 60%, 40%); }

Dart: A short introduction to dart.

On 1/28/2012 I was fortunate to give an introduction to dart at a GTUGsf Mobile HTML5 Codelab event. Conrad Wade did a spectacular job of arranging the event and promoting the DartSF meetup group. I truly enjoy the GTUGsf events!

Dart: Updated Dartium builds with breakpoint support for Linux and Mac

As Seth Ladd has commented on google plus, Dartium now has breakpoint support. Big win in such an early stage of the project. Providing Release builds for Mac and Linux below. While I was trying breakpoints out, one thing noticed was to getting scripts to show up properly in inspector you need to hit an extra refresh on the page. My public is can be found on pgp.mit.edu.

wget http://dl.dropbox.com/u/33138127/dartium_macosx/Chromium.app.tar.gz
wget http://dl.dropbox.com/u/33138127/dartium_macosx/Chromium.app.tar.gz.sig
wget http://dl.dropbox.com/u/33138127/dartium_macosx/Chromium.app.tar.gz.md5
wget http://dl.dropbox.com/u/33138127/dartium_macosx/README.txt
gpg --verify Chromium.app.tar.gz.sig Chromium.app.tar.gz
md5sum -c Chromium.app.tar.gz.md5
wget http://gsdview.appspot.com/dart-editor-archive-continuous/latest/DartBuild-linux.gtk.x86.zip
wget http://dl.dropbox.com/u/33138127/dartium/dartium-linux-32bit-Release.tar.gz
wget http://dl.dropbox.com/u/33138127/dartium/dartium-linux-32bit-Release.tar.gz.sig
wget http://dl.dropbox.com/u/33138127/dartium/dartium-linux-32bit-Release.tar.gz.md5
wget http://dl.dropbox.com/u/33138127/dartium/README.txt
gpg --verify dartium-linux-32bit-Release.tar.gz.sig dartium-linux-32bit-Release.tar.gz
md5sum -c dartium-linux-32bit-Release.tar.gz.md5

Dart: Example of WebGL on Dart

My hacking attempts with webgl on dart has made me revert to using ‘dart:dom’. While I really enjoy ‘dart:html’, one might not be able to use some of the more important webgl methods. The reason would be the missing constructors on Float32Array, an issue has been filed. For now the following sample with code could help guide those excited to play with webgl on dart. Thank you Learning WebGL for the sample code work with.

Dart: fillstyle on cavnas

To be able to draw on canvas in Dart you need two things. A canvas element defined and a canvas rendering context to draw on. In this example we use a CanvasRenderingContext2D to fillstyle a set of rectangles with rgb colors of size x and y. Modified for Dart, mozilla developer example can be done the following way. Check a live example here.

    <canvas id="canvas" width="600" height="600"></canvas>
    <script type="text/javascript" src="CanvasFillstyleExample.dart.app.js"></script>
  draw() {
    var ctx = document.query('canvas').getContext('2d');
    for (var i=0;i<6;i++){
      for (var j=0;j<6;j++){
        ctx.fillStyle = 'rgb(' + (255-42.5*i).floor().toString() + ',' + 
                         (255-42.5*j).floor().toString() + ',0)';

Dart: CSS3 Slider Carousel

The slider carousel by html5rocks now comes with an example in dart. I may have loaded to many  images into the single page, might take a few seconds to load. The source code can be found on github. Dart provides a simpler way to deal with client side programming, cleaner syntax and simple access to the DOM. Go Dart!