# Creating OOT module

**URL:** <https://www.ruby-forum.com/t/creating-oot-module/230499>\
**Category:** GNU Radio\
**Created:** [June 20, 2014, 11:42am UTC](https://www.ruby-forum.com/t/creating-oot-module/230499 "2014-06-20T11:42:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**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, 11:42am UTC](https://www.ruby-forum.com/t/creating-oot-module/230499/1 "2014-06-20T11:42:53Z")

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Hi

I have written a block in python and was trying to create an out of tree  
module as given in the gnuradio tutorial.  
While using cmake …/ the following error occured.  
CMake Error: CMake can not determine linker language for  
target:gnuradio-dec  
CMake Error: Cannot determine link language for target “gnuradio-dec”.

this was rectified by removing the lib directory and the cmake file was  
created without error. Then i run the make install and found following  
error:

Scanning dependencies of target \_dec\_swig  
[46%] Building CXX object  
swig/CMakeFiles/\_dec\_swig.dir/dec\_swigPYTHON\_wrap.cxx.o  
Linking CXX shared module \_dec\_swig.so  
/usr/bin/ld: cannot find -lgnuradio-dec  
collect2: error: ld returned 1 exit status  
make[2]: \*\*\* [swig/\_dec\_swig.so] Error 1  
make[1]: \*\*\* [swig/CMakeFiles/\_dec\_swig.dir/all] Error 2  
make: \*\*\* [all] Error 2

what should i do to rectify this linking error…

Regards

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**Author:** ![sreena\_p\_h](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@sreena\_p\_h](https://www.ruby-forum.com/u/sreena_p_h)\
**Post date:** [June 20, 2014, 11:47am UTC](https://www.ruby-forum.com/t/creating-oot-module/230499/2 "2014-06-20T11:47:04Z")

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Hi Sreena,

1. have you added your block using gr\_modtool? otherwise, cmake won’t  
notice it’s there.
2. if you have, what version of GNU Radio are you using? Support for  
python-only OOT modules have but recently been added.

Greetings,  
Marcus