attribute

attribute
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Name

attribute — Sets an attribute of the object that contains it.

Synopsis

LZX: attribute
Type: Class
Access: public
Topic: LZX.Basics

Description

The attribute tag has two uses:

In a class definiiton, the attribute tag defines an attribute that can be set in instances of the class.
```
<canvas height="30">
  <class name="mybutton" extends="button">
   
  </class>
  <mybutton text="before" myattr="after"
            onclick="setAttribute('text', this.myattr)"/>
</canvas>
```

In an instance, the attribute tag attaches an attribute to the instance. The attribute can be accessed from script.

<canvas height="30">

  <class name="mybutton" extends="button">
      <attribute name="myattr" type="string" value="after"/>
  </class>
  <mybutton text="before" 
            onclick="setAttribute('text', this.myattr)">
    
  </mybutton>
</canvas>

See the Developer's Guide for a complete discussion.

Also see the documentation for class and the general description of LZX attributes. The Classes tutorial describes how to use attributes to define a class.

Superclass Chain

attribute

Known Subclasses

Details

Initial Attributes (6)

Initial Attributes are given as attributes in LZX but are not generally available as properties in JavaScript.

name

The name of the attribute.

required

True if this is a required attribute.

setter

Code that is executed when setAttribute is used to set the value of this attribute. This code is executed within a context in which the variable with this attribute's name is bound to the value passed to setAttribute.

type

The type of the attribute. This determines how the value is parsed. Attributes of type string are automatically quoted if when="immediate", for any other value of when, a literal string would have to be quoted to be used as a value.

value

The initial value of the attribute. The type of this value is specified by the value of the type attribute; if that attribute is not present, it's the type of this attribute in this element's tag. The attribute is given this value when the element is created.

when

When the initial value expression is to be evaluated. One of:

@c{immediately}: evaluate when the enclosing element is defined (must be a constant)
@c{once}: evaluate when the enclosing element is initialized
@c{always}: update whenever the value of the expression changes

The default is @c{when="immediately"}. The setting for @c{when} can be overridden when assigning a value to an attribute by using the syntax


                           attribute
                                           name=$when
                                           value{expression}

. The default for when value is @c{always}, for example:

<view
                                        title="$once{computeTitle()}" />

sets the title of the view to a computed value and <view title="${parent.subtitle}" \> will cause the title of the view to track @c{parent.subtitle}.

LZX Synopsis

Copyright © 2002-2007 Laszlo Systems, Inc. All Rights Reserved. Unauthorized use, duplication or distribution is strictly prohibited. This is the proprietary information of Laszlo Systems, Inc. Use is subject to license terms.

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