c-library functions should be always present, documented, and lowercase

doc/src/Library_utility.rst

@@ -19,6 +19,7 @@ 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_python_api_version`
 
 The :cpp:func:`lammps_free` function is a clean-up function to free
 memory that the library had allocated previously via other function
@@ -100,3 +101,9 @@ where such memory buffers were allocated that require the use of
 
 .. doxygenfunction:: lammps_get_last_error_message
    :project: progguide
+
+-----------------------
+
+.. doxygenfunction:: lammps_python_api_version
+   :project: progguide
+

python/lammps/mliap/loader.py

@@ -58,7 +58,7 @@ def activate_mliappy(lmp):
     try:
         library = lmp.lib
         module_names = ["mliap_model_python_couple", "mliap_unified_couple"]
-        api_version = library.lammps_PYTHON_API_VERSION()
+        api_version = library.lammps_python_api_version()
         
         for module_name in module_names:
             # Make Machinery

src/library.cpp

@@ -57,6 +57,10 @@
 #include "exceptions.h"
 #endif
 
+#if defined(LMP_PYTHON)
+#include <Python.h>
+#endif
+
 using namespace LAMMPS_NS;
 
 // for printing the non-null pointer argument warning only once
@@ -5571,12 +5575,28 @@ int lammps_get_last_error_message(void *handle, char *buffer, int buf_size) {
   return 0;
 }
 
-#ifdef LMP_PYTHON
-#include <Python.h>
-int lammps_PYTHON_API_VERSION(){
+/* ---------------------------------------------------------------------- */
+
+/** Return API version of embedded Python interpreter
+
+\verbatim embed:rst
+This function is used by the ML-IAP python code (mliappy) to verify
+the API version of the embedded python interpreter of the PYTHON
+package.  It returns -1 if the PYTHON package is not enabled.
+
+.. versionadded:: TBD
+
+\endverbatim
+ *
+ * \return   PYTHON_API_VERSION constant of the python interpreter or -1 */
+
+int lammps_python_api_version() {
+#if defined(LMP_PYTHON)
   return PYTHON_API_VERSION;
-}
+#else
+  return -1;
 #endif
+}
 
 // Local Variables:
 // fill-column: 72

src/library.h

@@ -256,9 +256,7 @@ 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);
 
-#ifdef LMP_PYTHON
-int lammps_PYTHON_API_VERSION();
-#endif
+int lammps_python_api_version();
 
 #ifdef __cplusplus
 }