Creating block using gr


I am working with gnuradio 3.3.0 and now trying to create new block

I am able to do following :
sudo make install
sudo ldconfig

after editing header file of bin and lib with .cc file.

Then while using newly created block with GRC I got following error

def init(self, *args, **kwargs): raise AttributeError(“No
constructor defined”) AttributeError: No constructor defined

Detail I have posted here. Is this error due to lower version of
GNURadio, if not how can I solve this.

Please help me out.

Sent from Windows Mail

Hi Dilip,

3.3.0 is an old version of gnuradio. The code you posted clearly
contains GR 3.7 code structure;
so you’re using an 3.7 gr_modtool with an 3.3.0 GNU Radio; this can’t

Please use the gr_modtool that comes with your GNU Radio version (there
was no official gr_modtool back in the 3.3.0
days in the GR tree). It is not desirable to use such an old version of
GR unless you really need to support legacy code, therefore you should
try to use GNU Radio 3.7; please install the latest versions using
PyBOMBS ( or

Happy exploring,
Marcus M.