Howto:Create animation XML files from Nasal

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Objective: Use Nasal scripting to dynamically create an XML file by using the setprop() API call to set up your XML file's PropertyList-encoded structure and then writing the result to the file system using the write_properties() wrapper.

Getting started

The following piece of Nasal creates a new XML file:

 var location= "/temp/test/foo";
 var filename="test.xml";
 setprop(location, "hello world");
 write_properties(filename, location);

The created output is:

 <?xml version="1.0"?>
 <PropertyList>
  <temp>
   <test>
    <foo>hello world</foo>
   </test>
  </temp>

Once you understand how this works, you can dynamically create PropertyList-encoded XML files for your instruments.

       <path>vsd.ac</path>
       <animation>
          <type>select</type>
          <object-name>vsd</object-name>
          <condition>
             <greater-than-equals>
                <property>systems/electrical/outputs/efis</property>
                <value>9</value>
             </greater-than-equals>
          </condition>
       </animation>

For example, to create the snippet of XML procedurally, you can use this:

    var location = "/temp/test/";
    var filename="xmltest.xml";
    setprop(location~"path", "vsd.ac");
    setprop(location~"animation/type", "select");
    setprop(location~"animation/object-name", "vsd");
    setprop(location~"animation/condition/greather-than-equals/property", "systems/electrical/outputs/efis");
    setprop(location~"animation/condition/greather-than-equals/value", "9");
    io.write_properties(filename, location);