How to set filter stopband attenuation for a block in gnuradio companion?

I would like to set the stopband attenuation value for a bandpass filter in GNU Radio Companion. The standard Band Pass Filter block does not allow to set this parameter, but uses a default.

Does anybody know how this could be done?

I tried the following:

searched for various filter blocks and filter tap calculator blocks in GNU Radio Companion: could not find any that allows to set this parameter, even though the underlying filter coefficient calculator functions have such input.
created an Embedded Python Block and tried to use it to wrap the filter coefficient calculator (gnuradio.filter.optfir.complex_band_pass) that allows setting this parameter and the filter (gnuradio.filter.fft_filter_ccc) that uses the coefficients to do the filtering. Somehow the filter's work method cannot be called properly from the wrapper block's work method.

Solution

you don't need to write an embedded block to use the Filter design tools GNU Radio brings – you can just use Python as the "taps" parameter of an existing FIR filter block (instead of just typing in your filter tap vector, e.g. [1,2,3,4]), i.e., add an "Import" block, where you from gnuradio.filter import optfir, and use optfir.whatever(...) as "Taps" parameter.

Other than that, GNU Radio's forte is not designing specialized filters, honestly :) I do recomment the excellent pyFDA; I'd install it locally using

python3 -m venv filter-design
source ./filter-design/bin/activate
pip3 install pyfda
pyfdax

and use it to design your favorite filter, if you don't need to re-design it programmatically on the fly.