slides-uptodate

<macrodef name='slides-uptodate'>
  <attribute name='source'/>
  <attribute name='destdir'/>
  <attribute name='property'/>
  <attribute name='result' default='${index}'/>
  <sequential>
    <uptodate property='@{property}'
              srcfile='@{source}'
              targetfile='@{destdir}/@{result}'/>
  </sequential>
</macrodef>