have Error::set_show_error() return the previous setting

doc/src/Library_utility.rst

@@ -20,6 +20,7 @@ functions.  They do not directly call the LAMMPS library.
 - :cpp:func:`lammps_force_timeout`
 - :cpp:func:`lammps_has_error`
 - :cpp:func:`lammps_get_last_error_message`
+- :cpp:func:`lammps_set_show_error`
 - :cpp:func:`lammps_python_api_version`
 
 The :cpp:func:`lammps_free` function is a clean-up function to free
@@ -110,6 +111,11 @@ where such memory buffers were allocated that require the use of
 
 -----------------------
 
+.. doxygenfunction:: lammps_set_show_error
+   :project: progguide
+
+-----------------------
+
 .. doxygenfunction:: lammps_python_api_version
    :project: progguide
 

python/lammps/core.py

@@ -348,6 +348,7 @@ class lammps(object):
     self.lib.lammps_get_last_error_message.argtypes = [c_void_p, c_char_p, c_int]
     self.lib.lammps_get_last_error_message.restype = c_int
     self.lib.lammps_set_show_error.argtypes = [c_void_p, c_int]
+    self.lib.lammps_set_show_error.restype = c_int
 
     self.lib.lammps_extract_global.argtypes = [c_void_p, c_char_p]
     self.lib.lammps_extract_global_datatype.argtypes = [c_void_p, c_char_p]
@@ -2139,6 +2140,8 @@ class lammps(object):
 
     :param flag: enable (1) or disable (0) printing of error message
     :type flag: int
+    :return: previous setting of the flag
+    :rtype: int
     """
     self.lib.lammps_set_show_error(self.lmp, flag)
 

src/error.cpp

@@ -315,9 +315,12 @@ void Error::set_last_error(const char *msg, ErrorType type)
 /* ----------------------------------------------------------------------
    enable or disable printing error messages. for use with library interface.
    if flag = 0 only last error message and type are updated.
+   returns the previous setting.
 ------------------------------------------------------------------------- */
 
-void Error::set_show_error(const int flag)
+int Error::set_show_error(const int flag)
 {
+  int oldflag = show_error
   showerror = flag;
+  return oldflag;
 }

src/error.h

@@ -98,7 +98,7 @@ 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);
+  int set_show_error(const int flag);
 
  private:
   std::string last_error_message;

src/library.cpp

@@ -7342,17 +7342,21 @@ This function can be used to stop LAMMPS from printing error messages
 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`.
+:cpp:func:`lammps_get_last_error_message`.  The function returns the
+previous setting so that one can easily override the setting
+temporarily and restore it afterwards.
 
 \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
+ * \return  previous setting of the flag
  */
-void lammps_set_show_error(void *handle, const int flag)
+int lammps_set_show_error(void *handle, const int flag)
 {
   LAMMPS *lmp = (LAMMPS *) handle;
-  if (lmp && lmp->error) lmp->error->set_show_error(flag);
+  if (lmp && lmp->error) return lmp->error->set_show_error(flag);
+  return 1; // default value
 }
 
 /* ---------------------------------------------------------------------- */

src/library.h

@@ -312,7 +312,7 @@ void lammps_force_timeout(void *handle);
 
 int lammps_has_error(void *handle);
 int lammps_get_last_error_message(void *handle, char *buffer, int buf_size);
-void lammps_set_show_error(void *handle, const int flag);
+int lammps_set_show_error(void *handle, const int flag);
 
 int lammps_python_api_version();