How to provide Scripting support for Qt-Applications?

Question

I'm looking for a scripting language which can be integrated into my Qt5 Application. The application has a public api, which can be used to extend the application with plugins. Now I want to add a scripting language to the application which provides access to the whole public api. The scripting language must fulfill the following Requirements :

• Script Code can be executed from within the QT-Application.
• The user can access the file-system, network and create graphical elements from the scripting language.
• The user can access the public api of my QT Application through bindings.
• There should be a generator available to automatically generate script-language bindings for my public api.
• For classes that are part of the Public Api, it should be possible to pass around objects between the QT-Application and the Scripting Engine.

I evaluated the following Script-Languages:

• Qt-Script , together with the QT-Script Generator.
  The scripting language is based on ECMAScript/Javascript and can easily be integrated into QT apps. This fulfills all my requirements and works as expected. The generator can be used to generate bindings for the QT-Api itself and to generate bindings for the public api of my application. Sadly the qt-script module is going to be deprecated with qt5.5 and the scriptgenerator is no longer maintained .
• Python
  There seem to be several python-qt bindings available.
  Pyside would probably be ok, but it seems to be inactive as well. Apart from that I would have to embed python into c++, which is not supported by pyside out of the box, but could be done by the python c api.

What scripting-languages and tools do you suggest, that fulfills all my requirements?

Answer 1

SWIG with Python seems to be a good choice. SWIG is still actively maintained.

Although SWIG doesn't fulfill all of my requirements out of the box, it shouldn't be that a big thing to make all of them work:

Script Code can be executed from within the QT-Application.

This is not supported out of the box. You have to embed a python interpreter into your application. https://docs.python.org/2/extending/embedding.html

The user can access the file-system, network and create graphical elements from the scripting language.

Accessing the filesystem and network should not be a problem with python. To create graphical userinterfaces, there are a lot of libraries available:
https://wiki.python.org/moin/GuiProgramming

• The user can access the public api of my QT Application through bindings.
• There should be a generator available to automatically generate script-language bindings for my public api.

This is done by SWIG. They provide great C++ and c++11 support.

• http://www.swig.org/Doc3.0/SWIGPlus.html
• http://www.swig.org/Doc3.0/CPlusPlus11.html

For classes that are part of the Public Api, it should be possible to pass around objects between the QT-Application and the Scripting Engine.

This is possible using the c++ functions provided by swig:

• SWIG_TypeQuery gets you information about C++ types
• SWIG_NewPointerObj converts a c++ object to a python (proxy) object
• SWIG_ConvertPtr converts a python (proxy) object back to c++ object

More info in the External runtime chapter