Disable DLL interface for CADET < v5. This will break tests with CADE…

…T < v5.

cadet/cadet.py

@@ -219,6 +219,7 @@ def __init__(self, install_path: Optional[Path] = None, use_dll: bool = False, *
             self._cadet_dll_runner: Optional[CadetDLLRunner] = CadetDLLRunner(
                 self.cadet_dll_path
             )
+            self._ensure_compatible_dll_version()
         else:
             self._cadet_dll_runner: Optional[CadetCLIRunner] = None
             self.use_dll = use_dll
@@ -271,7 +272,26 @@ def install_path(self, install_path: Optional[os.PathLike]) -> None:
             self._cadet_cli_runner = CadetCLIRunner(self.cadet_cli_path)
         if self.cadet_dll_path is not None:
             self._cadet_dll_runner = CadetDLLRunner(self.cadet_dll_path)
+            self._ensure_compatible_dll_version()
 
+    def _ensure_compatible_dll_version(self):
+        """
+        Ensure that the CADET DLL version is compatible with the required interface.
+
+        Raises
+        ------
+        RuntimeError
+            If `use_dll` is `True` and the CADET version is outdated (less than 5), indicating that
+            the DLL interface is not supported.
+        """
+        if int(self._cadet_dll_runner.cadet_version[0]) < 5:
+            if self.use_dll:
+                raise RuntimeError(
+                    f"CADET was set to `use_dll` but found outdated CADET "
+                    f"version {self._cadet_dll_runner.cadet_version} "
+                    f"which does not support the DLL interface."
+                )
+            self._cadet_dll_runner = None
 
     @property
     def cadet_path(self) -> Optional[Path]:

cadet/cadet_dll.py

@@ -1,6 +1,7 @@
 import ctypes
 import io
 import os
+import warnings
 from pathlib import Path
 from typing import Any, Optional
 
@@ -1645,6 +1646,13 @@ def __init__(self, dll_path: os.PathLike | str) -> None:
         cdtGetLibraryBuildType.restype = ctypes.c_char_p
         self._cadet_build_type = cdtGetLibraryBuildType().decode('utf-8')
 
+        if int(self._cadet_version[0]) < 5:
+            warnings.warn(
+                f"The detected CADET installation with version {self._cadet_version}"
+                " is below version 5.0 and does not support the DLL interface."
+            )
+            return
+
         # Define the log handler callback type
         self.LOG_HANDLER_CLBK = ctypes.CFUNCTYPE(
             None,
@@ -1684,6 +1692,9 @@ def clear(self) -> None:
 
         This method deletes the current simulation results and resets the driver.
         """
+        if int(self._cadet_version[0]) < 5:
+            return
+
         if hasattr(self, "res"):
             del self.res
 
@@ -1694,6 +1705,8 @@ def __del__(self) -> None:
         """
         Clean up the CADET driver on object deletion.
         """
+        if int(self._cadet_version[0]) < 5:
+            return
         self._api.deleteDriver(self._driver)
 
     def setup_log_buffer(self, log_level: int = None) -> io.StringIO: