From d41d5960e49eaf375fed10b89ed610b59299929f Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Thu, 11 Aug 2022 04:07:49 -0400
Subject: [PATCH] simplify and modernize

---
 src/H5MD/dump_h5md.cpp | 13 ++++---------
 src/H5MD/dump_h5md.h   |  2 +-
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/src/H5MD/dump_h5md.cpp b/src/H5MD/dump_h5md.cpp
index 1ee2bd2a54..2bb5af3043 100644
--- a/src/H5MD/dump_h5md.cpp
+++ b/src/H5MD/dump_h5md.cpp
@@ -73,7 +73,7 @@ DumpH5MD::DumpH5MD(LAMMPS *lmp, int narg, char **arg) : Dump(lmp, narg, arg)
   format_default = nullptr;
   flush_flag = 0;
   unwrap_flag = 0;
-  datafile_from_dump = -1;
+  other_dump = nullptr;
   author_name = nullptr;
 
   every_dump = utils::inumeric(FLERR,arg[3],false,lmp);
@@ -141,11 +141,8 @@ DumpH5MD::DumpH5MD(LAMMPS *lmp, int narg, char **arg) : Dump(lmp, narg, arg)
       }
       if (box_is_set||create_group_is_set)
         error->all(FLERR, "Cannot set file_from in dump h5md after box or create_group");
-      int idump;
-      for (idump = 0; idump < output->ndump; idump++)
-        if (strcmp(arg[iarg+1],output->dump[idump]->id) == 0) break;
-      if (idump == output->ndump) error->all(FLERR,"Cound not find dump_modify ID");
-      datafile_from_dump = idump;
+      other_dump = dynamic_cast<DumpH5MD *>(output->get_dump_by_id(arg[iarg+1]));
+      if (!other_dump) error->all(FLERR,"Cound not find dump_modify H5MD dump ID {}", arg[iarg+1]);
       do_box=false;
       create_group=false;
       iarg+=2;
@@ -262,7 +259,7 @@ void DumpH5MD::openfile()
   }
 
   if (me == 0) {
-    if (datafile_from_dump<0) {
+    if (!other_dump) {
       if (author_name==nullptr) {
         datafile = h5md_create_file(filename, "N/A", nullptr, "lammps", LAMMPS_VERSION);
       } else {
@@ -296,8 +293,6 @@ void DumpH5MD::openfile()
         h5md_write_string_attribute(particles_data.group, "charge", "type", "effective");
       }
     } else {
-      DumpH5MD* other_dump;
-      other_dump=(DumpH5MD*)output->dump[datafile_from_dump];
       datafile = other_dump->datafile;
       group_name_length = strlen(group->names[igroup]);
       group_name = new char[group_name_length];
diff --git a/src/H5MD/dump_h5md.h b/src/H5MD/dump_h5md.h
index 6634cdb8ae..e33f64f54a 100644
--- a/src/H5MD/dump_h5md.h
+++ b/src/H5MD/dump_h5md.h
@@ -35,9 +35,9 @@ class DumpH5MD : public Dump {
   int natoms, ntotal;
   int unwrap_flag;    // 1 if atom coords are unwrapped, 0 if no
   h5md_file datafile;
-  int datafile_from_dump;
   h5md_particles_group particles_data;
   char *author_name;
+  DumpH5MD *other_dump;
 
   bool do_box;
   bool create_group;