For AltDSS: fix reprocess_buses_callback; should refactor to move it there

Author: PMeira

docs/changelog.md

@@ -7,10 +7,11 @@ relevant. See [DSS C-API's repository](https://github.com/dss-extensions/dss_cap
 
 ### 0.15.3
 
-Released on 2024-02-23.
+Released on 2024-02-26.
 
 - Upgrade the backend to [**DSS C-API 0.14.2**](https://github.com/dss-extensions/dss_capi/releases/tag/0.14.2). There are a couple of minor fixes, including for `Lines.Parent`.
 - `patch_dss_com`: Allow the DSS instance to be callable for better compatibility with our DSS engine. Note that this won't have performance benefits nor handles complex scripts.
+- Fix Bus callback integration with AltDSS-Python. The relevant code should be moved there later.
 
 ### 0.15.2
 

dss/__init__.py

@@ -23,15 +23,13 @@
 
 DssException = DSSException
 
-# Bind to the FFI module instance for OpenDSS-v7
-api_util: CffiApiUtil = CffiApiUtil(ffi, lib) #: API utility functions and low-level access to the classic API
-
 if not hasattr(lib, 'ctx_New'):
     # Module was built without the context API
+    api_util: CffiApiUtil = CffiApiUtil(ffi, lib) #: API utility functions and low-level access to the classic API
     prime_api_util = None
     DSS_GR: IDSS = IDSS(api_util) #: GR (Global Result) interface
 else:
-    prime_api_util = CffiApiUtil(ffi, lib, lib.ctx_Get_Prime()) #: API utility functions and low-level access for DSSContext API
+    api_util = prime_api_util = CffiApiUtil(ffi, lib, lib.ctx_Get_Prime()) #: API utility functions and low-level access for DSSContext API
     DSS_GR: IDSS = IDSS(prime_api_util) #: GR (Global Result) interface using the new DSSContext API
 
 DSS_IR: IDSS = DSS_GR #: IR was removed in DSS-Python v0.13.x, we'll keep mapping it to DSS_GR for this version

dss/_cffi_api_util.py

@@ -360,31 +360,51 @@ def __init__(self, ffi, lib, ctx=None):
         self.register_callbacks()
 
 
+    def _check_for_error(self, result=None):
+        """
+        Checks for a DSS engine error (on the default configuration).
+
+        By default, raises an exception if any error is detected, otherwise returns the `result` parameter.
+        
+        If the user disabled exceptions, any error is simply ignored. Note that, in this case, manually
+        calling this function would have no purpose/effects.
+
+        Note that, **in the future**, we may try showing a popup form like the official OpenDSS does on Windows
+        if AllowForms is True. This behavior is not very portable though and not adequate for automated scripts.
+        """
+        if self._errorPtr[0] and Base._use_exceptions:
+            error_num = self._errorPtr[0]
+            self._errorPtr[0] = 0
+            raise DSSException(error_num, self.get_string(self.lib.Error_Get_Description()))
+            
+        return result
+
+
     def reprocess_buses_callback(self, step: int):
         '''
         Used internally to remap buses to Python objects after the bus list is built.
         '''
         if self._is_clearing:
             return
-        
+
         if step == 0:
             # Drop dead references
             self._bus_refs = [b for b in self._bus_refs if b() is not None]
 
             # Create a name to object dict, dropping the weakref wrapper
-            self._bus_ref_to_name = {
-                b(): b().name
+            self._bus_ref_to_name = [
+                (b(), b().Name)
                 for b in self._bus_refs
-            }
+            ]
             return
 
         if step != 1:
             return
 
         # Now try to remap the objects; on exception, just invalidate everything
         try:
-            ptrs = self._lib.Alt_Bus_GetListPtr()
-            names = self._check_for_error(self._get_string_array(self._lib.Circuit_Get_AllBusNames))
+            ptrs = self.lib.Alt_Bus_GetListPtr()
+            names = self._check_for_error(self.get_string_array(self.lib.Circuit_Get_AllBusNames))
         except:
             for bus_ref in self._bus_refs:
                 bus_ref()._invalidate_ptr()
@@ -393,6 +413,14 @@ def reprocess_buses_callback(self, step: int):
             return
 
         self._bus_refs.clear()
+
+        if len(names) == 0:
+            # No buses to rebind, invalidate all
+            for old_bus, _ in self._bus_ref_to_name:
+                old_bus._invalidate_ptr()
+
+            return
+
         name_to_new_ptr = {name: ptrs[idx] for idx, name in enumerate(names)}
         for old_bus, old_name in self._bus_ref_to_name:
             new_ptr = name_to_new_ptr.get(old_name)
@@ -497,6 +525,9 @@ def init_buffers(self):
         # also keep a casted version for complex floats
         self.gr_cfloat64_pointers = (self.ffi.cast('double _Complex**', tmp_float64_pointers[0][0]), tmp_float64_pointers[1][0])
 
+        self._errorPtr = self.lib.Error_Get_NumberPtr()
+
+
     def clear_buffers(self):
         self.lib.DSS_DisposeGRData()
         self.lib.DSS_ResetStringBuffer()