add method that allows suppressing printing error messages immediately

src/error.cpp

@@ -35,7 +35,7 @@ static std::string truncpath(const std::string &path)
 /* ---------------------------------------------------------------------- */
 
 Error::Error(LAMMPS *lmp)
-  : Pointers(lmp), numwarn(0), maxwarn(100), allwarn(0)
+  : Pointers(lmp), numwarn(0), maxwarn(100), allwarn(0), showerror(1)
 {
   last_error_message.clear();
   last_error_type = ERROR_NONE;
@@ -56,7 +56,7 @@ void Error::universe_all(const std::string &file, int line, const std::string &s
   } catch (fmt::format_error &) {
     ; // do nothing
   }
-  if (universe->me == 0) {
+  if (showerror && (universe->me == 0)) {
     if (universe->uscreen)  fputs(mesg.c_str(),universe->uscreen);
     if (universe->ulogfile) fputs(mesg.c_str(),universe->ulogfile);
   }
@@ -84,7 +84,10 @@ void Error::universe_one(const std::string &file, int line, const std::string &s
 {
   std::string mesg = fmt::format("ERROR on proc {}: {} ({}:{})\n",
                                  universe->me,str,truncpath(file),line);
-  if (universe->uscreen) fputs(mesg.c_str(),universe->uscreen);
+  if (showerror) {
+    if (universe->uscreen) fputs(mesg.c_str(),universe->uscreen);
+    if (universe->ulogfile) fputs(mesg.c_str(),universe->ulogfile);
+  }
   utils::flush_buffers(lmp);
 
   // allow commands if an exception was caught in a run
@@ -131,7 +134,7 @@ void Error::all(const std::string &file, int line, int failed, const std::string
 
   if (failed > NOLASTLINE) mesg += utils::point_to_error(input, failed);
   if (failed == ARGZERO) mesg += utils::point_to_error(input, 0);
-  if (me == 0) utils::logmesg(lmp,mesg);
+  if (showerror && (me == 0)) utils::logmesg(lmp,mesg);
   utils::flush_buffers(lmp);
 
   // allow commands if an exception was caught in a run
@@ -164,11 +167,12 @@ void Error::one(const std::string &file, int line, int failed, const std::string
   std::string mesg = fmt::format("ERROR on proc {}: {} ({}:{})\n", me, str, truncpath(file), line);
   if (failed > NOPOINTER) mesg += utils::point_to_error(input, failed);
   if (failed == ARGZERO) mesg += utils::point_to_error(input, 0);
-  utils::logmesg(lmp,mesg);
+  if (showerror) utils::logmesg(lmp,mesg);
 
-  if (universe->nworlds > 1)
-    if (universe->uscreen)
-      fputs(mesg.c_str(),universe->uscreen);
+  if (showerror && (universe->nworlds > 1)) {
+    if (universe->uscreen) fputs(mesg.c_str(),universe->uscreen);
+    if (universe->ulogfile) fputs(mesg.c_str(),universe->ulogfile);
+  }
 
   utils::flush_buffers(lmp);
   // allow commands if an exception was caught in a run
@@ -213,8 +217,7 @@ void Error::warning(const std::string &file, int line, const std::string &str)
 {
   ++numwarn;
   if ((maxwarn != 0) && ((numwarn > maxwarn) || (allwarn > maxwarn) || (maxwarn < 0))) return;
-  std::string mesg = fmt::format("WARNING: {} ({}:{})\n",
-                                 str,truncpath(file),line);
+  std::string mesg = fmt::format("WARNING: {} ({}:{})\n", str,truncpath(file),line);
   if (screen) fputs(mesg.c_str(),screen);
   if (logfile) fputs(mesg.c_str(),logfile);
 }
@@ -308,3 +311,13 @@ void Error::set_last_error(const char *msg, ErrorType type)
   last_error_message = msg;
   last_error_type = type;
 }
+
+/* ----------------------------------------------------------------------
+   enable or disable printing error messages. for use with library interface.
+   if flag = 0 only last error message and type are updated.
+------------------------------------------------------------------------- */
+
+void Error::set_show_error(const int flag)
+{
+  showerror = flag;
+}

src/error.h

@@ -98,12 +98,13 @@ class Error : protected Pointers {
   std::string get_last_error() const;
   ErrorType get_last_error_type() const;
   void set_last_error(const char *msg, ErrorType type = ERROR_NORMAL);
+  void set_show_error(const int flag);
 
  private:
   std::string last_error_message;
   ErrorType last_error_type;
 
-  int numwarn, maxwarn, allwarn;
+  int numwarn, maxwarn, allwarn, showerror;
   // internal versions that accept explicit fmtlib arguments
   [[noreturn]] void _all(const std::string &, int, int, fmt::string_view, fmt::format_args args);
   [[noreturn]] void _one(const std::string &, int, int, fmt::string_view, fmt::format_args args);

src/library.cpp

@@ -89,7 +89,7 @@ static void ptr_argument_warning()
 
 [[noreturn]] static void lammps_throw_error(const std::string &fname, const std::string &mesg)
 {
-  throw LAMMPSException("ERROR in library function " + fname + "(): " + mesg + "\n");
+  throw LAMMPSException("ERROR in " + fname + "(): " + mesg + "\n");
   exit(1);
 }
 
@@ -130,7 +130,7 @@ template <typename... ARgs>
    END_CAPTURE
 ------------------------------------------------------------------------- */
 
-#define BEGIN_CAPTURE \
+#define BEGIN_CAPTURE        \
   Error *error = lmp->error; \
   try
 
@@ -327,7 +327,8 @@ multiple LAMMPS instances concurrently or sequentially.  See
 void lammps_close(void *handle)
 {
   auto lmp = (LAMMPS *) handle;
-  delete lmp;
+  // only delete if not already deleted
+  if (lmp && lmp->comm) delete lmp;
 }
 
 /* ---------------------------------------------------------------------- */
@@ -7200,6 +7201,35 @@ int lammps_has_error(void *handle)
 
 /* ---------------------------------------------------------------------- */
 
+/** Enable or disable direct printing of error messages
+
+\verbatim embed:rst
+
+.. versionadded:: TBD
+
+This function can be used to stop LAMMPS from printing error messages
+*before* LAMMPS throws a :ref:`C++ exception <exceptions>`.  This is so
+it may be left to the code calling the library interface whether to
+check for them, and retrieve and print error messages using the library
+interface functions :cpp:func:`lammps_has_error` and
+:cpp:func:`lammps_get_last_error_message`.
+
+\endverbatim
+ *
+ * \param handle   pointer to a previously created LAMMPS instance cast to ``void *`` or NULL
+ * \param flag     enable (not 0) or disable (0) printing error messages before throwing exception
+ */
+void lammps_set_show_error(void *handle, const int flag)
+{
+  if (handle) {
+    LAMMPS *lmp = (LAMMPS *) handle;
+    Error *error = lmp->error;
+    error->set_show_error(flag);
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
 /** Copy the last error message into the provided buffer
 
 \verbatim embed:rst
@@ -7287,5 +7317,5 @@ int lammps_python_api_version() {
 }
 
 // Local Variables:
-// fill-column: 80
+// fill-column: 99
 // End: