This chapter is from the book
This chapter is from the book
This chapter is from the book
3.38 param
|
Element type |
param |
|
Attributes |
expr | name | type | value | valuetype |
|
Parents |
object | subdialog |
|
Children |
None. |
|
Description |
Specifies name/value pairs that are passed into the parent object or subdialog. |
DTD
<!ELEMENT param EMPTY > <!ATTLIST param name NMTOKEN #REQUIRED expr %expression; #IMPLIED value CDATA #IMPLIED valuetype (data | ref) 'data' type CDATA #IMPLIED >
Language model
Attributes
-
expr : expression
An ECMAScript expression for the parameter value.
-
name : NMTOKEN
The name associated with the parameter.
-
type : CDATA
Specifies a MIME type (used when valuetype is ref).
-
value : CDATA
The parameter value.
-
valuetype : (data | ref) = ref
There are two value types, data and ref. The type data indicates the value is data, and ref indicates the value references an URI.
Children
None.
Examples
Example 3-44 A subdialog call parameterized with param elements
<?xml version="1.0" encoding="iso-8859-1"?>
<vxml version="1.0">
<form>
<subdialog name="result" src="#returnevent">
<catch event="returnevent.event">
<prompt>
Received return event from subdialog, test complete.
</prompt>
<assign name="result" expr="true"/>
</catch>
<param name="param" expr="'parameter'"/>
<prompt>
Calling subdialog that returns an event, passing a parameter.
</prompt>
</subdialog>
</form>
<form id="returnevent">
<var name="param"/>
<block>
<prompt>
In subdialog, received <value expr="param"/>, returning event.
</prompt>
<return event="returnevent.event"/>
</block>
</form>
</vxml>
Notice that Example 3-44 shows a subdialog that returns by throwing an event. The calling dialog can catch this event. Returning by throwing an event does not fill the calling subdialog form item, however. We need explicitly fill result in the catch block. If we don't do this, the calling dialog will loop forever as result would never get filled.