# Why SWIG has been selected as C++ wrapper for Python for GNURadio? **URL:** \ **Category:** GNU Radio\ **Created:** [June 20, 2014, 10:35am UTC](https://www.ruby-forum.com/t/why-swig-has-been-selected-as-c-wrapper-for-python-for-gnuradio/230496 "2014-06-20T10:35:12Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [June 20, 2014, 10:35am UTC](https://www.ruby-forum.com/t/why-swig-has-been-selected-as-c-wrapper-for-python-for-gnuradio/230496/1 "2014-06-20T10:35:12Z")
Hi All This is a question intended for the Software designers and maintainers of the GNURadio Is there a specific reason / advantage of using SWIG as a C++ wrapper over using other avaialble wrappers for C++ as Boost.Python , Cython etc … in the context of GNURadio ? Thanks! Joe ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 20, 2014, 11:23am UTC](https://www.ruby-forum.com/t/why-swig-has-been-selected-as-c-wrapper-for-python-for-gnuradio/230496/2 "2014-06-20T11:23:53Z")
On 06/20/2014 10:34 AM, Joe D wrote: > This is a question intended for the Software designers and maintainers > of the GNURadio > > Is there a specific reason / advantage of using SWIG as a C++ wrapper > over using other avaialble wrappers for C++ as Boost.Python , Cython > etc … in the context of GNURadio ? First, you need to realize that the decision to use SWIG was made a long way back, when there were less alternatives. At the time, one important argument was that Python wasn’t the only scripting language that was to be supported. At this point, we know a lot of SWIG’s quirks, and there is little reason to change. It does all we need (although it could do somethings a bit faster, the build times are still annoying), and it integrates well with our code structure. To be honest: Few of us are 100% happy with SWIG, but it’s the devil we know 🙂 However, while there are alternatives to SWIG worth considering, Cython is not suitable for what we need. I haven’t looked into Boost.Python closely, though. M ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 20, 2014, 11:44am UTC](https://www.ruby-forum.com/t/why-swig-has-been-selected-as-c-wrapper-for-python-for-gnuradio/230496/3 "2014-06-20T11:44:05Z")
Hi Joe, Disclaimer: I haven’t been around when SWIG was introduced into GNU Radio. These are somewhat educated guesses, but since I’ve had _some_ fun with SWIG, I wondered myself and this is what I rationalized. - SWIG was around at the time GNU Radio was rewritten, which must have been around 2004. I think the choice to use SWIG was made before that [1]. SWIG has been around since '96, so I guess it was expected to be somewhat stable/reliable. Boost.Python was started in '03, and if the guys behind it decided that they had to conceptually rework something, the second year it exists sounds like a dangerous time to use it. ctypes is (I think) python-2.5esque, so this couldn’t have been around back in the day, and only does basic C wrapping. - It does what GNU Radio needed: Generate python wrapper classes without the developers needing to actually write code; defining the interface was enough for a “normal” block to be SWIG’ed, and specialized wrapper classes only had to be written for some of the core things so that things like connect()ing blocks would work. It is arguable if writing and maintaining the SWIG .i files (especially since we’re talking about the autohell era) was worth the trouble of avoiding that, but for the only comparable competitor Boost.Python, you had to define wrapper classes, and references to the classes wrapped and their members. Pyrex/Cython now is a complete different language and would have made GNU Radio something much more multi-paradigmatic, whilst adding even more to the “active” codebase that had to be maintained by hand. - It was expected that if SWIG wasdone right, GNU Radio could end up with multiple scripting language interfaces [2]. Nowadays, people are content to use python, especially since we now (feels like yesterday) have support to write gr::block classes in python, which of course needed a lot of gateway work, so (to my knowledge) there haven’t been efforts to make use of more than the C++ and Python SWIG capabilities[3]. Greetings, Marcus [1] [http://lists.gnu.org/archive/cgi-bin/namazu.cgi?query=SWIG&submit=Search!&idxname=discuss-gnuradio&max=20&result=normal&sort=date%3Aearly](http://lists.gnu.org/archive/cgi-bin/namazu.cgi?query=SWIG&submit=Search!&idxname=discuss-gnuradio&max=20&result=normal&sort=date%3Aearly) [2] [http://lists.gnu.org/archive/html/discuss-gnuradio/2003-03/msg00135.html](http://lists.gnu.org/archive/html/discuss-gnuradio/2003-03/msg00135.html) [3] After all, for scripting python works really nice and is easy to learn. If you wanted to use a fast Matrix operation in Fortran, there is no stopping you from doing that from C++, which is the programming language of choice for performance-critical blocks, anyway, as long as your Fortran and C++ compilers are ABI-compliant. If you wanted ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 20, 2014, 7:24pm UTC](https://www.ruby-forum.com/t/why-swig-has-been-selected-as-c-wrapper-for-python-for-gnuradio/230496/4 "2014-06-20T19:24:27Z")
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**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 20, 2014, 4:25pm UTC](https://www.ruby-forum.com/t/why-swig-has-been-selected-as-c-wrapper-for-python-for-gnuradio/230496/5 "2014-06-20T16:25:41Z")
On Fri, Jun 20, 2014 at 5:42 AM, Marcus Müller [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > decided that they had to conceptually rework something, the second year it > competitor Boost.Python, you had to define wrapper classes, and references > > choice for performance-critical blocks, anyway, as long as your Fortran and > in the context of GNURadio ? > > Thanks! > Joe Martin and Marcus nicely answered the question for you. Just wanted to say that while we’re not entirely impressed with some features of SWIG, the fact that it’s working well for us and the disruption we would cause switching it out is not worth it. We’d have to make sure that the changes would result in a perfect 1-to-1 match with what we’re exporting using swig. Tom ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 21, 2014, 9:50am UTC](https://www.ruby-forum.com/t/why-swig-has-been-selected-as-c-wrapper-for-python-for-gnuradio/230496/6 "2014-06-21T09:50:32Z")
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