Python Module

This module embeds Python into GTlab. Python is an interpreted programming language that is suitable for script programming. Scripts are small programs that are usually implemented within one source code file. A Python Interpreter reads the source code file and executes the instructions defined in them. The Python Module offers the possibility to define and execute process chains by using Python. This increases the flexibility of process chains and enables the extension of GTlab's preliminary design calculation methods without source code access and C++ knowledge. To use these advantages the Python Module extends GTlab by the following three interfaces.

• Python Console

  The Python Module integrates a Python Console into GTlab. This is available via the Python Console tab next to the Application tab (Fig. 1). The Python Console allows you to navigate through projects and read and modify data from the central data model using Python code. It provides an automatic completion that suggests available objects and functions.

  

• Python Script Calculator

  The Python Script Calculator is a calculator element which can be integrated into process chains. The wizard of the Python Script Calculator provides an editor for defining Python scripts (Fig. 2). When creating scripts using this editor all data model packages can be accessed. So it is possible to read and modify data from the central data model. To identify errors the editor offers the possibility to evalute the script (Ctrl+E). The evaluation is also necessary to register newly defined variables, classes and methods in the Python context. After evaluation the newly defined components are available via automatic completion. Output messages that results from the evaluation are displayed on the console below the editor. Note that any changes to data model objects that result from the evaluation are not transferred to the central data model. The data transfer will only happen, if the Python Script Calculator is executed as part of a process chain. In this case the output messages are displayed on the Python Console described above (Fig. 1). The benefit of the Python Script Calculator is to integrate and test new calculation methods during the runtime of GTlab. No recompiling of program parts is necessary.

  

• Python Task

  The Python Task enables the creation and execution of process chains in the form of Python scripts. The wizard of the Python Task also provides an editor for defining Python scripts (Fig. 3). It offers the same functionality as the editor of the Python Script Calculator. In addition it allows the instantiation, configuration and execution of calculators. For this the wizards of all available calculators can be called by using the 'Add' button. If the configuration of a calculator via its wizard is completed, the Python code corresponding to the configuration will be automatically inserted into the editor. A calculator instance can be executed by calling its run() method. During the evaluation (Ctrl+E) the run() method returns False and the calculators are not executed. The calculators are only executed when the Python Task is executed via process control. The benefit of this task is to enable the flexible interconnection of calculators. The calculators can be executed iteratively and depending on previously calculated result data. All advantages of Python are available for additional calculations and modifications of the data model.

  

License

The largest portion of the code is licensed under the Apache 2.0 License.

Smaller thirdparty party code part of code base uses other permissive licenses, such as the BSD and MIT licenses. Please review the directory LICENSES and .reuse for a full overview on all licensed used.

Compiling from Source

Prerequisites

A working GTlab installation is required. This includes GTlab and the GTlab Logging library. In addition, the Qt toolkit need to be installed to build the Python module.

The Python module uses the PythonQt library to embed the Python interpreter into GTlab and provide access to GTlab's data model structure and the slots of all classes. PythonQt will be automatically downloaded and built by the Python module. If you want to use your own installation of PythonQt, use BUILD_BUNDLED_PYTHONQT=OFF in the CMake configuration.

Building

The python module requires a recent CMake (>3.15) to build. The configuration and build process is similar to other CMake builds:

cmake -S . -B build_dir -DQt5_DIR=<path/to/cmake/Qt5> -DCMAKE_PREFIX_PATH=<path/to/gtlab_install> -DCMAKE_INSTALL_PREFIX=<path/to/gtlab_install>
cmake --build build_dir
cmake --build build_dir --target install