Re: [Discuss-gnuradio] Problem with undefined symbol in new block created by gr_modtool in 3.7.2

[Nowlan, Sean]

The first place I'd look is in your_block.h. Did you remember to declare any 
public member functions to be pure virtual in that file, and then declare your 
(non-virtual) functions in your_block_impl.h? If you forgot to declare pure 
virtual functions, i.e., "virtual return_type your_block(args_list) = 0;" in 
your_block.h, it will compile but you will get the undefined symbol at runtime.

This probably a common pitfall and it might be worth making a note in the wiki 
for OutOfTreeModules. I'll add that.

Architects of gr_modtool... can you add an autogen comment in *.h files 
reminding the user to declare pure virtual functions? I think users who don't 
deeply understand OO and particularly its  C++ syntax would benefit from this 
reminder. I think it's a common paradigm to use other examples to fill in the 
"guts" of gr_modtool generated C++ code, but things like this are easy to miss.

Sean

-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Marcus Müller
Sent: Wednesday, March 05, 2014 3:21 PM
To: George Sklivanitis; GNURadio Discussion List
Subject: Re: [Discuss-gnuradio] Problem with undefined symbol in new block 
created by gr_modtool in 3.7.2

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Hi George,
This is a little unspecific. Most probably you have a problem similar to the 
fftw- related problem of activecat, but that's only guessing... Please heed 
http://gnuradio.org/redmine/projects/gnuradio/wiki/ReportingErrors when 
reporting errors.
Greetings,
Marcus

On March 5, 2014 8:57:46 PM CET, George Sklivanitis <address@hidden> wrote:
>Hello all,
>
>I am dealing with the problem of undefined symbol when trying to 
>execute a python script for testing my new custom block created in GNU 
>Radio 3.7.2.
>I used gr_modtool for creating the new block and also followed the 
>instructions posted at
>
>http://gnuradio.org/redmine/projects/gnuradio/wiki/OutOfTreeModulesConf
>ig
>
>for correctly configuring it but the problem still holds.
>
>Any ideas?
>
>Thanks,
>-George
>
>--
>Sklivanitis Georgios
>
>
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