Re: [Discuss-gnuradio] AttributeError: 'function' object has no attribute 'to_basic_block' ? (GR 3.7.0)

[Monahan-Mitchell, Tim]

> I've stepped up to GR 3.7.0, re-used gr_modtool to freshly re-create my OOT 
> module, everything builds, tests, installs OK. GRC has my OOT blocks listed 
> and I can put them on my flowgraph.

> One of my OOT blocks is a function that takes in shorts and outputs shorts (a 
> 1-to-2 interpolator).

> I have a simple flowgraph created in GRC:   File Source -> My block -> File 
> sync .

> GRC is happy until I run the flowgraph, and I get this:

> Executing: "<....> /top_block.py"

> Traceback (most recent call last):
>   File "<....> /top_block.py", line 54, in <module>
>     tb = top_block()
>   File "<....> /top_block.py", line 39, in __init__
>     self.connect((self.my_block_s_to_s_0, 0), (self.blocks_file_sink_0, 0))
>   File "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/top_block.py", 
> line 130, in connect
>     self._connect(points[i-1], points[i])
>   File "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/top_block.py", 
> line 141, in _connect
>     self._tb.primitive_connect(src_block.to_basic_block(), src_port,
> AttributeError: 'function' object has no attribute 'to_basic_block'

An update.

First, I believe I exhaustively eradicated older installed versions of GR by 
searching and deleting for anything named '*gnuradio*' under /usr, re-built GR 
and re-installed. But, same results.

Using the pdb single step debugger and also just looking at the code, I have a 
question about top_block.py (under 
/usr/local/lib/python2.7/dist-packages/gnuradio/gr):

    def _connect(self, src, dst):
        (src_block, src_port) = self._coerce_endpoint(src)
        (dst_block, dst_port) = self._coerce_endpoint(dst)
        self._tb.primitive_connect(src_block.to_basic_block(), src_port,
                                   dst_block.to_basic_block(), dst_port)

    def _coerce_endpoint(self, endp):
        if hasattr(endp, 'to_basic_block'):
            return (endp, 0)
        else:
            if hasattr(endp, "__getitem__") and len(endp) == 2:
                return endp # Assume user put (block, port)
            else:
                raise ValueError("unable to coerce endpoint")

I'm not a python expert, but "_coerce_endpoint" is checking if the attribute 
'to_basic_block' exists... But then the "_connect" function goes right ahead 
and tries to use it as it prepares to call "primitive_connect", which is what 
the error is about... And single stepping through the python code seems to 
verify that...  (in my case, the test for __getitem__ and len(endp) == 2 is the 
path the code takes).

I also don't understand why "_coerce_endpoint" in that path returns ony "endp", 
but in its other leg, returns "(endp, 0)"? Seems like the caller wants to 
assign 2 values (src_block, src_port)...

This part of the top_block.py code is the same between 3.6.4.2 and 3.7.0...