Re: Embedded Python Block Tutorial Param ID Error

[Solomon Tan]

Hi Sebastian,

Thanks for the reply. I could rerun the flowchart by deleting the epy python
files and the __pycache__ subdirectory, close and reopen GRC. It would allow me
to run it once more before the same Param ID error appeared. So i suppose it is
that commit that is responsible (but I dont know how to confirm it).

Whats interesting though is that I notice that the same patch was included in
maint3.9 but I did not encounter this problem at all with the code I compiled
from maint3.9. I only had this problem with the master branch as of my first
email today.

I would love to fix this bug but I just started using GRC so Im still unfamiliar
with the software. Would you like me to open an Issue on Github to make it
easier for the gr-dev team to solve the issue?

Cheers,
Sol

On 8/5/21 3:40 pm, Sebastian Koslowski wrote:
> Hi, 
> 
> that looks like a bug introduced by
> https://github.com/gnuradio/gnuradio/pull/4522
> <https://github.com/gnuradio/gnuradio/pull/4522>
> We forgot to special-case / adapt epy blocks...
> 
> Sebastian
> 
> (von unterwegs gesendet)
> 
> On Sat, May 8, 2021, 06:23 Solomon Tan <solomonbstoner@yahoo.com.au
> <mailto:solomonbstoner@yahoo.com.au>> wrote:
> 
>     Dear all,                       
>                                                     
>     I was following the GNURadio Embedded Python Block Tutorial. After adding 
> a     
>     Python block, I got the following error.                                  
>       
>     ```                                                                       
>       
>     Param - Id(id):                                                           
>       
>             ID "epy_block_0" is blacklisted.                                  
>       
>     ```                                                                       
>       
>     The parameter ID of the Python block is marked in red. Why and how? The 
>     weirdest thing is that the Python block worked initially at first. I could
>     run the
>     flowgraph, but after stopping it, I couldnt rerun it again. I was given 
> that
>     Param
>     ID error. My code was almost equivalent to the template, so it cant be my 
> fault
>     , right?
>     ```
>     """
>     Embedded Python Blocks:
>     """
>     import numpy as np
>     from gnuradio import gr
> 
>     class blk(gr.sync_block):  
>         """Embedded Python Block example - a simple multiply const"""
> 
> 
>         def __init__(self, example_param=1.0):  # only default arguments here
>             """arguments to this function show up as parameters in GRC"""
>             gr.sync_block.__init__(
>                 self,
>                 name='EPB Multiply by Const',   # will show up in GRC
>                 in_sig=[np.float32],
>                 out_sig=[np.float32]
>             )
>             # if an attribute with the same name as a parameter is found,
>             # a callback is registered (properties work, too).
>             self.example_param = example_param
> 
> 
>         def work(self, input_items, output_items):
>             """example: multiply with constant"""
>             output_items[0][:] = input_items[0] *2 * self.example_param
>             return len(output_items[0])
>     ```
> 
>     I could not find any other mail in the archive about this parameter ID 
> error.
> 
>     Thank you.
>     Cheers,
>     Sol
>