Ant: property name containing a timestamp

Question

Regarding the timestamp variable in the ant script, I can see how to build it using a macrodef, but I don't see the way to read it afterwards, even though its name was saved in a variable.

<macrodef name="macro1">
  <attribute name="propName"/>
  <attribute name="propValue"/>
  <sequential>
    <property name="@{propName}" value="@{propValue}"/>
    <echo>   dans macrodef $${@{propName}} : ${@{propName}}</echo>
    </sequential>
</macrodef>

<tstamp>                                                              
     <format property="rightNow" pattern="yyyyMMdd"  locale="en,UK" />
</tstamp>                        
<var name="nomProp" value="${rightNow}"/>
<macro1 propName="${rightNow}" propValue="at Paris"/>                 

When the property is named, it is ok, but this is useless :

<echo>property $${20170531} content : ${20170531}</echo>    

...so what is the trick to get it ? this syntax does not work

<echo> property $${nomProp} content : ${${nomProp}}</echo>