How to set minimum noutput_items for python custom blocks

Hello guys!

I'm trying to implement a python custom (general) block with the following in/out signature:

- in_sig=[(np.complex64, M)]

- out_sig=[np.complex64]

The block has three parameters: M, N and L.

The idea is to get 2D frames (N,M), do some signal processing, and output N*M+L serial samples for each frame.

I'm managing the input buffer using the following forecast function:

    def forecast(self, noutput_items, ninputs):
        noutput_frames = noutput_items//(self.M*self.N+self.L)
        ninput_items_required = [noutput_frames*self.N]
        return ninput_items_required

The problem I have is to force noutput_items greater or equal to N*M+L.

I tried self.set_min_noutput_items(N*M+L) running raises the following error:

self.set_min_noutput_items(N*M+L)

  File "/usr/lib/python3/dist-packages/gnuradio/gr/gateway.py", line 129, in __getattr__

    if not hasattr(self, "gateway"):

  File "/usr/lib/python3/dist-packages/gnuradio/gr/gateway.py", line 129, in __getattr__

    if not hasattr(self, "gateway"):

  File "/usr/lib/python3/dist-packages/gnuradio/gr/gateway.py", line 129, in __getattr__

    if not hasattr(self, "gateway"):

  [Previous line repeated 494 more times]

RecursionError: maximum recursion depth exceeded

Is it possible to set minimum noutput_items also for python blocks?

Thanks a lot.

Ivan