Thinking Hybrid - Python/C++ Integration

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Python Extending/Integrating A Real World Example Tips Summary Python where we can, C ++ where we must Source: http://xkcd.com/353/ Guy K. Kloss — Python where we can,C++ where we must 1/28
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    17-Aug-2014
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    Technology

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Talk on integrating native C++ sensibly into Python for ease of use of the code base. Inheriting from C++ classes, overriding functionality, automatically generating the bindings using Py++ and SCons. Code demonstrated in the presentation can be found here: http://www.kloss-familie.de/moin/TalksPresentations

Transcript of Thinking Hybrid - Python/C++ Integration

  • Python Extending/Integrating A Real World Example Tips Summary Python where we can, C++ where we must Source: http://xkcd.com/353/ Guy K. Kloss Python where we can,C++ where we must 1/28
  • Python Extending/Integrating A Real World Example Tips Summary Python where we can, C++ where we must Guy K. Kloss BarCamp Auckland 2007 15 December 2007 Quote: Alex Martelli, Senior Google Developer Guy K. Kloss Python where we can,C++ where we must 2/28
  • Python Extending/Integrating A Real World Example Tips Summary Outline 1 Python 2 Extending/Integrating 3 A Real World Example 4 Tips Guy K. Kloss Python where we can,C++ where we must 3/28
  • Python Extending/Integrating A Real World Example Tips Summary Outline 1 Python 2 Extending/Integrating 3 A Real World Example 4 Tips Guy K. Kloss Python where we can,C++ where we must 4/28
  • Python Extending/Integrating A Real World Example Tips Summary What is Python? Objectoriented Dynamic Easy to learn syntax High-level data types Scripting language Embeddable in C/C++ Guy K. Kloss Python where we can,C++ where we must 5/28
  • Python Extending/Integrating A Real World Example Tips Summary Python vs. Java (or C++) No compilation Fast editbuilddebug cycle Dynamic Typing No need to declare variables for use Easy Syntax No curly braces, no semicolons, no new . . . Embeddable Scripting support for your applications Interactive Create, view, change objects at runtime 50% less code Compact and natural syntax 300% more productive Closer to the way you think Guy K. Kloss Python where we can,C++ where we must 6/28
  • Python Extending/Integrating A Real World Example Tips Summary Why Python? Mixable Extend Python with components written in C++, Java, C Embed Python into your application and call it from C/C++ Platform independent Powerful Ease of use of scripting language Built-in object types Extensive libraries Automatic memory management Modules, classes and exceptions Guy K. Kloss Python where we can,C++ where we must 7/28
  • Python Extending/Integrating A Real World Example Tips Summary What is Python used for? System Utilities System admin tools, portable shell scripts Internet Scripting CGI scripts, parse HTML, process XML, email tools User Interfaces (UIs) & rapid prototyping Component Glue Scripting for apps, COM scripting Distributed Programming Web Services, COM, CORBA, XMLRPC Database Programming Scientic Computing PyODE, NumPy, SciPy, PyMol, . . . Image Processing Python Image Library OpenGL Programming, Writing Games PyOpenGL, Panda3D, PyOgre, Py3d, VisualPython Artical Intelligence Guy K. Kloss Python where we can,C++ where we must 8/28
  • Python Extending/Integrating A Real World Example Tips Summary Why Native Code? C/C++, Fortran (and Java, C#, ...) Performance Binding to legacy code (Existing) Applications/Libraries . . . ... want to be scripted ... want to be tested ... want to be re-used Guy K. Kloss Python where we can,C++ where we must 9/28
  • Python Extending/Integrating A Real World Example Tips Summary Outline 1 Python 2 Extending/Integrating 3 A Real World Example 4 Tips Guy K. Kloss Python where we can,C++ where we must 10/28
  • Python Extending/Integrating A Real World Example Tips Summary What if I could . . . Use this code more eectively . . . ? [NaSt2D demonstration (native executable)] Guy K. Kloss Python where we can,C++ where we must 11/28
  • Python Extending/Integrating A Real World Example Tips Summary Extending/Integration The Contestants: The classic way . . . Extending and Embedding the Python Interpreter The new way . . . Python ctypes SWIG Boost.Python Others: SIP Pythonizer SILOON (Pyrex) Extensions also for Java, C#, Fortran, . . . available Guy K. Kloss Python where we can,C++ where we must 12/28
  • Python Extending/Integrating A Real World Example Tips Summary Extending/Integration The Contestants: The classic way . . . Extending and Embedding the Python Interpreter The new way . . . Python ctypes SWIG Boost.Python Others: SIP Pythonizer SILOON (Pyrex) Extensions also for Java, C#, Fortran, . . . available Guy K. Kloss Python where we can,C++ where we must 12/28
  • Python Extending/Integrating A Real World Example Tips Summary Extending/Integration The Contestants: The classic way . . . Extending and Embedding the Python Interpreter The new way . . . Python ctypes SWIG Boost.Python Others: SIP Pythonizer SILOON (Pyrex) Extensions also for Java, C#, Fortran, . . . available Guy K. Kloss Python where we can,C++ where we must 12/28
  • Python Extending/Integrating A Real World Example Tips Summary Extending/Integration The Contestants: The classic way . . . Extending and Embedding the Python Interpreter The new way . . . Python ctypes SWIG Boost.Python Others: SIP Pythonizer SILOON (Pyrex) Extensions also for Java, C#, Fortran, . . . available Guy K. Kloss Python where we can,C++ where we must 12/28
  • Python Extending/Integrating A Real World Example Tips Summary Extending/Integration The Contestants: The classic way . . . Extending and Embedding the Python Interpreter The new way . . . Python ctypes SWIG Boost.Python Others: SIP Pythonizer SILOON (Pyrex) Extensions also for Java, C#, Fortran, . . . available Guy K. Kloss Python where we can,C++ where we must 12/28
  • Python Extending/Integrating A Real World Example Tips Summary Boost.Python Thinking Hybrid with Boost.Python Bottom up and . . . Top down possible Develop quickly Resolve bottle necks Donald Knuths: Premature optimisation is the root of all evil. or: Dont Optimise Now! Guy K. Kloss Python where we can,C++ where we must 13/28
  • Python Extending/Integrating A Real World Example Tips Summary Boost.Python Thinking Hybrid with Boost.Python Bottom up and . . . Top down possible Develop quickly Resolve bottle necks Donald Knuths: Premature optimisation is the root of all evil. or: Dont Optimise Now! Guy K. Kloss Python where we can,C++ where we must 13/28
  • Python Extending/Integrating A Real World Example Tips Summary Boost.Python Thinking Hybrid with Boost.Python Bottom up and . . . Top down possible Develop quickly Resolve bottle necks Donald Knuths: Premature optimisation is the root of all evil. or: Dont Optimise Now! Guy K. Kloss Python where we can,C++ where we must 13/28
  • Python Extending/Integrating A Real World Example Tips Summary Hello World char const* greet(unsigned x) { static char const* const msgs[] = {quot;helloquot;, quot;Boost.Pythonquot;, quot;world!quot;}; if (x > 2) { throw std::range error(quot;greet: Index out of range.quot;); } return msgs[x]; } #include using namespace boost::python; BOOST PYTHON MODULE(hello) { .def(quot;greetquot;, greet, quot;return one of 3 parts of a greetingquot;); } And here it is in action: >>> import hello >>> for x in range(3): ... print hello.greet(x) ... hello Boost.Python world! Guy K. Kloss Python where we can,C++ where we must 14/28
  • Python Extending/Integrating A Real World Example Tips Summary Boost.Python One of a few libraries that make it easy to integrate C++ and Python code How does it pull o this trick? Template metaprogramming (i. e. Dont ask!) Guy K. Kloss Python where we can,C++ where we must 15/28
  • Python Extending/Integrating A Real World Example Tips Summary Boost.Python One of a few libraries that make it easy to integrate C++ and Python code How does it pull o this trick? Template metaprogramming (i. e. Dont ask!) Guy K. Kloss Python where we can,C++ where we must 15/28
  • Python Extending/Integrating A Real World Example Tips Summary See it Happen Im making it work for you now . . . [MyClass demonstration (MyClass.cpp, MyClass.h, mymodule.cpp)] Guy K. Kloss Python where we can,C++ where we must 16/28
  • Python Extending/Integrating A Real World Example Tips Summary Outline 1 Python 2 Extending/Integrating 3 A Real World Example 4 Tips Guy K. Kloss Python where we can,C++ where we must 17/28
  • Python Extending/Integrating A Real World Example Tips Summary A Real World Example Re-visiting NaSt2D Wrapping NaSt2D Control the code Guy K. Kloss Python where we can,C++ where we must 18/28
  • Python Extending/Integrating A Real World Example Tips Summary NaSt2D in Python This is what Im going to show you: Code to be wrapped Generated wrapper code Generator script SCons (build system) How it works with Python [Wrapped NaSt2D demonstration (Wrapper.h, nast2dmodule.cpp, generate bindings.py, SConstruct, demo0.py)] Guy K. Kloss Python where we can,C++ where we must 19/28
  • Python Extending/Integrating A Real World Example Tips Summary Extend Wrapper Class Inheriting from C++ classes Interfacing numerical values Change functionality Follow the Computation Guy K. Kloss Python where we can,C++ where we must 20/28
  • Python Extending/Integrating A Real World Example Tips Summary Overriding in Python This is what Im going to show you: Overriding a native method in Python Native method needs to be virtual Live data plotting with GNUplot [NaSt2D with plotting demonstration (demo1.py, demo2.py)] Guy K. Kloss Python where we can,C++ where we must 21/28
  • Python Extending/Integrating A Real World Example Tips Summary Do more Computations Parameter Study Change input le Compute several cases Plot results automatically Guy K. Kloss Python where we can,C++ where we must 22/28
  • Python Extending/Integrating A Real World Example Tips Summary Automating in Python This is what Im going to show you: Using a template input le Batchcalculating several runs Plotting results with GNUplot [NaSt2D with parameter variation demonstration (demo3.py, demo4.py)] Guy K. Kloss Python where we can,C++ where we must 23/28
  • Python Extending/Integrating A Real World Example Tips Summary Outline 1 Python 2 Extending/Integrating 3 A Real World Example 4 Tips Guy K. Kloss Python where we can,C++ where we must 24/28
  • Python Extending/Integrating A Real World Example Tips Summary Tips To override C++ methods: make them virtual C/C++ pit fall Call by reference/value Solution: calling policies Map to other/sane languages Java: Jython C#: IronPython Fortran: PyFort, Py2F (Native to other: SWIG) Guy K. Kloss Python where we can,C++ where we must 25/28
  • Python Extending/Integrating A Real World Example Tips Summary Summary Why is Python good for you? How can performance bottle necks be resolved? Advantages of Thinking Hybrid Pythonnative wrapping using Boost.Python Automated wrapper generation SCons build system Guy K. Kloss Python where we can,C++ where we must 26/28
  • Python Extending/Integrating A Real World Example Tips Summary Python and the Need for Speed Cuong Do Software Architect YouTube.com Python is fast enough for our site and allows us to produce maintainable features in record times, with a minimum of developers. Guy K. Kloss Python where we can,C++ where we must 27/28
  • Python Extending/Integrating A Real World Example Tips Summary Questions? [email protected] Guy K. Kloss Python where we can,C++ where we must 28/28