[ModelicaSystem] direct access to the class variable _omc_process

* do not use get_omc_process() within the class

Author: syntron

OMPython/ModelicaSystem.py

@@ -424,13 +424,13 @@ def model(
         if model_file is not None:
             file_path = pathlib.Path(model_file)
             # special handling for OMCProcessLocal - consider a relative path
-            if isinstance(self.get_omc_process(), OMCProcessLocal) and not file_path.is_absolute():
+            if isinstance(self._omc_process(), OMCProcessLocal) and not file_path.is_absolute():
                 file_path = pathlib.Path.cwd() / file_path
             if not file_path.is_file():
                 raise IOError(f"Model file {file_path} does not exist!")
 
             self._file_name = self.getWorkDirectory() / file_path.name
-            if (isinstance(self.get_omc_process(), OMCProcessLocal)
+            if (isinstance(self._omc_process(), OMCProcessLocal)
                     and file_path.as_posix() == self._file_name.as_posix()):
                 pass
             elif self._file_name.is_file():
@@ -1148,12 +1148,12 @@ def plot(
         plot is created by OMC which needs access to the local display. This is not the case for docker and WSL.
         """
 
-        if not isinstance(self.get_omc_process(), OMCProcessLocal):
+        if not isinstance(self._omc_process(), OMCProcessLocal):
             raise ModelicaSystemError("Plot is using the OMC plot functionality; "
                                       "thus, it is only working if OMC is running locally!")
 
         if resultfile is not None:
-            plot_result_file = self.get_omc_process().omcpath(resultfile)
+            plot_result_file = self._omc_process().omcpath(resultfile)
         elif self._result_file is not None:
             plot_result_file = self._result_file
         else:
@@ -1553,7 +1553,7 @@ def convertMo2Fmu(
         properties = (f'version="{version}", fmuType="{fmuType}", '
                       f'fileNamePrefix="{fileNamePrefix}", includeResources={include_resources_str}')
         fmu = self._requestApi(apiName='buildModelFMU', entity=self._model_name, properties=properties)
-        fmu_path = self.get_omc_process().omcpath(fmu)
+        fmu_path = self._omc_process().omcpath(fmu)
 
         # report proper error message
         if not fmu_path.is_file():
@@ -1574,7 +1574,7 @@ def convertFmu2Mo(
         >>> convertFmu2Mo("c:/BouncingBall.Fmu")
         """
 
-        fmu_path = self.get_omc_process().omcpath(fmu)
+        fmu_path = self._omc_process().omcpath(fmu)
 
         if not fmu_path.is_file():
             raise ModelicaSystemError(f"Missing FMU file: {fmu_path.as_posix()}")