From b016b135fa836547994e8615b922e5fd666836be Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Thu, 23 Jan 2025 04:51:12 -0500
Subject: [PATCH] added Compute::modify_param() function.

This way individual computes can add custom keywords to compute_modify in
a similar fashion as fixes
---
 doc/src/Modify_compute.rst | 2 ++
 src/compute.cpp            | 7 ++++++-
 src/compute.h              | 1 +
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/doc/src/Modify_compute.rst b/doc/src/Modify_compute.rst
index bf580a6561..ea603985dd 100644
--- a/doc/src/Modify_compute.rst
+++ b/doc/src/Modify_compute.rst
@@ -45,6 +45,8 @@ class.  See compute.h for details.
 +-----------------------+------------------------------------------------------------------+
 | pair_tally_callback   | callback function for *tally*\ -style computes (optional).       |
 +-----------------------+------------------------------------------------------------------+
+| modify_param          | called when a compute_modify request is executed (optional)      |
++-----------------------+------------------------------------------------------------------+
 | memory_usage          | tally memory usage (optional)                                    |
 +-----------------------+------------------------------------------------------------------+
 
diff --git a/src/compute.cpp b/src/compute.cpp
index d703cbfe6a..255e4ba1f2 100644
--- a/src/compute.cpp
+++ b/src/compute.cpp
@@ -149,7 +149,12 @@ void Compute::modify_params(int narg, char **arg)
       if (iarg+2 > narg) error->all(FLERR,"Illegal compute_modify command");
       dynamic_user = utils::logical(FLERR,arg[iarg+1],false,lmp);
       iarg += 2;
-    } else error->all(FLERR,"Illegal compute_modify command");
+    } else {
+      int n = modify_param(narg-iarg, &arg[iarg]);
+        if (n== 0)
+          error->all(FLERR, iarg + 1, "Compute {} {} does not support compute_modify {} command",
+                     id, style, arg[iarg]);
+    }
   }
 }
 
diff --git a/src/compute.h b/src/compute.h
index 0b077d7695..870d9ae088 100644
--- a/src/compute.h
+++ b/src/compute.h
@@ -113,6 +113,7 @@ class Compute : protected Pointers {
   Compute(class LAMMPS *, int, char **);
   ~Compute() override;
   void modify_params(int, char **);
+  virtual int modify_param(int, char **) { return 0; }
   virtual void reset_extra_dof();
 
   void init_flags();