Adapt program options in order to read in multiple dd4hep geometry description files

Core/include/ACTFW/Utilities/Options.hpp

@@ -11,7 +11,8 @@
 
 #include <string>
 
-using read_range = std::vector<double>;
+using read_range   = std::vector<double>;
+using read_strings = std::vector<std::string>;
 
 namespace std {
 std::ostream&
@@ -22,6 +23,15 @@ operator<<(std::ostream& os, const read_range& vec)
   }
   return os;
 }
+
+std::ostream&
+operator<<(std::ostream& os, const read_strings& vec)
+{
+  for (auto item : vec) {
+    os << item << " ";
+  }
+  return os;
+}
 }
 
 #endif  // ACTFW_OPTIONS_H

Plugins/DD4hep/include/ACTFW/Plugins/DD4hep/DD4hepDetectorOptions.hpp

@@ -31,12 +31,13 @@ namespace Options {
   {
     opt.add_options()(
         "dd4hep-input",
-        po::value<std::string>()->default_value(
-            "file:Detectors/DD4hepDetector/compact/FCChhTrackerTkLayout.xml"),
-        "The location of the input DD4hep file, use 'file:foo.xml'")(
-        "dd4hep-envelopeR",
-        po::value<double>()->default_value(0.),
-        "The envelop cover in R for DD4hep volumes.")(
+        po::value<read_strings>()->multitoken()->default_value(
+            {"file:Detectors/DD4hepDetector/compact/FCChhTrackerTkLayout.xml"}),
+        "The locations of the input DD4hep files, use 'file:foo.xml'. In case "
+        "you want to read in multiple files, just seperate the strings by "
+        "space.")("dd4hep-envelopeR",
+                  po::value<double>()->default_value(0.),
+                  "The envelop cover in R for DD4hep volumes.")(
         "dd4hep-envelopeZ",
         po::value<double>()->default_value(0.),
         "The envelop cover in z for DD4hep volumes.")(
@@ -62,12 +63,12 @@ namespace Options {
     // DETECTOR configuration:
     // --------------------------------------------------------------------------------
     FW::DD4hep::GeometryService::Config gsConfig("GeometryService", logLevel);
-    gsConfig.xmlFileName = vm["dd4hep-input"].template as<std::string>();
-    gsConfig.bTypePhi    = Acts::equidistant;
-    gsConfig.bTypeR      = Acts::arbitrary;
-    gsConfig.bTypeZ      = Acts::equidistant;
-    gsConfig.envelopeR   = vm["dd4hep-envelopeR"].template as<double>();
-    gsConfig.envelopeZ   = vm["dd4hep-envelopeZ"].template as<double>();
+    gsConfig.xmlFileNames = vm["dd4hep-input"].template as<read_strings>();
+    gsConfig.bTypePhi     = Acts::equidistant;
+    gsConfig.bTypeR       = Acts::arbitrary;
+    gsConfig.bTypeZ       = Acts::equidistant;
+    gsConfig.envelopeR    = vm["dd4hep-envelopeR"].template as<double>();
+    gsConfig.envelopeZ    = vm["dd4hep-envelopeZ"].template as<double>();
     gsConfig.buildDigitizationModules
         = vm["dd4hep-digitizationmodules"].template as<bool>();
     return gsConfig;