Python module: object as a reference (just as "Block ID" in "Function Probe" block)

[Lukas Haase]

Hi,

I am using the "Embedded Python Block" to create a simple controller that 
controls my USRP Source/Sink blocks.
These blocks support a message interface but unfortunately this is pretty 
useless except for the simplest applications (I need to control advanced tuning 
with timed commands, GPIO ports etc).

Hence I need to call the methods of these objects directly but I need a 
reference to them inside my custom block.
Within my python block I cannot reference the parent blocks, hence I need to 
pass a reference to these two objects via the constructor (and parameters).
Basically I want to do the same as parameter "Block ID" from the block 
"Function Probe" does.

What is the best way to implement this?

Thanks,
Luke






PS: Example:

class blk(gr.sync_block):  # other base classes are basic_block, decim_block, 
interp_block
    def __init__(self, sample_rate=1.0, usrp_source_block=''):  # only default 
arguments here
        """arguments to this function show up as parameters in GRC"""
        gr.sync_block.__init__(
            self,
            name='Controller',   # 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.sample_rate = sample_rate
                self.usrp_source_block = usrp_source_block

                # here I want to execute for example
                self.usrp_source_block.set_gain(5.0)

When I then create an USRP Sink object with ID uhd_usrp_sink_0 and enter as 
parameter I get the error:

Param - Usrp Source Block(usrp_source_block):
        Value "uhd_usrp_sink_0" cannot be evaluated:
        name 'uhd_usrp_sink_0' is not defined