resources/msi/parameters.wxi.erb

<?xml version="1.0" encoding="utf-8"?>
<Include>
  <?define VersionNumber="<%= version %>" ?>
  <?define DisplayVersionNumber="<%= display_version %>" ?>
  <?define UpgradeCode="<%= upgrade_code %>" ?>
<% parameters.each do |key, value| -%>
  <?define <%= key %>="<%= value %>" ?>
<% end -%>
</Include>