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Component Model Strawman: Declarative Syntax: Difference between revisions

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= Element Registration =
= Element Registration =


Let’s start from the minimum form of the element registration.
Moved to [[Component_Model_Strawman:_Element_Registration]]
Authors can use an <tt>element</tt> element to registering new element name.
Now agent recognizes <tt>x-comment</tt> as <tt>HTMLRegisteredElement</tt>.
This is just a plain old HTML element which has its own name.
 
<pre>
 
<head>
  <element for="x-comment"></element>
</head>
 
</pre>
 
== Scripting ==
 
The <tt>element</tt> element also provides an opportunity to give a behavior for the instance of the registered element.
 
<pre>
 
<head>
  <element for="x-comment"></element>
  <script>
  var e = document.head.querySelector(“[for=x-comment]”);
  e.close = function(element) {
    element.addEventListener(“click”, function(evt) {
      ..
    });
  };
  </script>
</head>
 
</pre>
 
Using  <tt>HTMLElementElement.register()</tt>, authors can register a set of lifecycle callbacks for each registered element.
There are two types of lifecycle event: <tt>open</tt> and <tt>close</tt>. The open is for creating the new instance of the <tt>Element</tt>.
You can override the constructor of the element by providing <tt>open</tt> callback.
The <tt>close</tt> callback provides the way to enhance created instance.
This is useful when you use given attributes to define the behavior.
 
To make the definition self-contained, we can put a <tt>script</tt> blocks inside an <tt>element</tt> element.
 
<pre>
 
<head>
  <element for="x-comment">
    <script>
      class Comment : HTMLElement {
          this.shadow = new ShawowRoot(this);
          ..;
      }
 
      HTMLElementElement.current.open = function() { return new Comment(); }});
    </script>
  </element>
</head>
 
</pre>
 
In this example, the script refers a static property called <tt>HTMLElementElement.current</tt>,
which points the enclosing <tt>element</tt> element.
This example also shows how we can provide an <tt>open</tt> lifecycle callback.
 
== Styling ==
 
The <tt>element</tt> element allows a <tt>style</tt> element as a child.
This <tt>style</tt> is part of the document stylesheet.
 
<pre>
 
<head>
  <element for="x-comment">
    <style>
    x-comment {
      color: gray;
    }
    </style>
  </element>
</head>
 
</pre>
 
= Shadow DOM Template =
 
An initial shape of new shadow tree can be defined using a <tt>template</tt> element.
 
<pre>
 
<head>
  <template id=”comment-template”>
    <div><content></content></div>
  </template>
</head>
 
</pre>
 
A <tt>template</tt> is instantiated through
 
* <tt>ShadowRoot</tt> constructor and
* <tt>shadow-template</tt> CSS property.
 
== The ShadowRoot constructor ==
 
The <tt>ShadowRoot</tt> constructor accepts a <tt>template</tt> element to instantiate.
 
<pre>
  ..
  this.shadow = new ShadowRoot(this, document.getElementById(“comment-template”));
  ..
</pre>
 
== The shadow-template CSS property  (brainstorming) ==
 
The template for shadow root also can be applied using CSS property.
 
<pre>
 
.comment {
  shadow-template: url('#comment-template');
}
 
</pre>
 
Note that imperatively-applied shadows always supersede shadows from the styling.
Also, there is no way to access style-originated shadows from the scripting environment.
 
== The Instantiation Event and Scripting ==
 
Even though the <tt>template</tt> can be used to define an extra visual representation for an element,
It would be useful if author can attach a script for the template-generated shadow tree.
 
The <tt>template</tt> element generates an <tt>instantiation</tt> event for
each template instantiation. Authors can listen it to setup event handlers for
generated elements by the template. The event doesn't bubble, and it isn't cancelable.
 
<pre>
 
<head>
  <template id=”comment-template”>
    <div><content></content></div>
  </template>
  <script>
  var e = document.getElementById("comment-template");
  e.addEventListener("instantiation", function(evt) {
    evt.root.querySelector("div").addEventListener("click", function(evt) { ... });
  });
  </script>
</head>
 
</pre>
 
A <tt>template</tt> element also allows a <tt>script</tt> element as a child,
whose script block can access <tt>HTMLTemplateElement.current</tt> to refer the enclosing <tt>template</tt> element.
 
<pre>
 
<head>
  <template id=”comment-template”>
    <div><content></content></div>
    <script>
    HTMLTemplateElement.current.addEventListener("instantiation", function(evt) {
      evt.root.querySelector("div").addEventListener("click", function(evt) { ... });
    });
    </script>
  </template>
</head>
 
</pre>


= Isolation =
= Isolation =


== Standalone Form ==
Moved to [[Component_Model_Strawman:_Isolation]]
 
The element registration and template definition are also done in a separate HTML.
Each HTML file which provides the element registration should have a <tt>provide</tt> attribute on the root html element.
This attribute prevents accidental loading of existing HTML files.
 
Effective markup vocabulary for the providing HTML is limited.
Agents only recognize a head element as a child of the root element when the HTML document is loaded as required.
 
<pre>
 
<html provide>
  <head>
    <element for="x-comment">..</element>
  </head>
</html>
 
</pre>
 
The host element can load the html with element definition using a <tt>link</tt> element with its <tt>rel</tt> attribute set to <tt>component</tt>.
 
<pre>
 
<html>
  <head>
    <link rel=”component” type=”text/html” href="comment.html">
  </head>
</html>
 
</pre>
 
The standalone definition can be done by a script file.
 
<pre>
 
<html>
  <head>
    <link rel=”component” type=”text/javascript” href="comment.js">
  </head>
</html>
 
</pre>
 
This is equivalent to linking to a HTML file of like:
 
<pre>
 
<html provide>
  <head>
    <script type=”text/javascript” src="comment.js"></script>
  </head>
</html>
 
</pre>
 
== Shared definition ==
 
In the default, these definitions are coming into the host document.
That means a providing HTML doesn’t have its own document nor the global object. Agents use these of the host document.
 
== Isolated definition ==
 
If the <tt>rel</tt> attribute contains the term <tt>isolate</tt>, the linked HTML is loaded as a separate document object.
The script inside the document is given a separate global object.
 
For the host document, there is no way to access the loaded document directly.
 
<pre>
 
<html>
  <head>
    <link rel=”component; isolate” type=”text/html” href="comment.html">
  </head>
</html>
 
</pre>
 
[[User:Rolandsteiner|RolandSteiner]] Should we make <tt>isolate</tt> an attribute on <tt>link</tt> rather than a <tt>rel</tt> value? As Dimitri mentioned, this could be useful in general and would allow us to branch it off into a separate spec.
 
[[User:Morrita|Morrita]] Any declarative syntax is a part of other spec. This is cross-cutting view of multiple proposals.

Latest revision as of 21:12, 27 October 2011

Element Registration

Moved to Component_Model_Strawman:_Element_Registration

Isolation

Moved to Component_Model_Strawman:_Isolation

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