Re: [Pcsim-users] Creating Synapses

[Pecevski D. <de...@ig...>]

Hi Nabeelah,

The problem that you reported occurs while downcasting of objects within 
the extension module C++ code, which are created from classes defined in 
the main PCSIM library. If the class defined in the main pcsim library 
has multiple inheritance, like in the case of LifNeuron (inherited from 
LifNeuronBase and CurrentInputTarget) then it seems that the downcasting 
to CurrentInputTarget doesn't work properly. Whether the class is 
defined through templates or not should not make any difference.

I've changed the code so that the downcasting always occurs in the main 
PCSIM library, checkout the latest revision from the repository.
If you want to implement your own synapse, for downcasting use the 
functions downcastCurrentInputTarget and downcastConductanceInputTarget. 
See how it is done in GenericCurrentBasedSpikingSynapse for an example.

regards,
Dejan



Miss Nabeelah Ali wrote:
>  Hi all,
>
> I am creating a new synapse class as an extension, however I cannot 
> use any synapses that I've 
> created and compiled from the extension module. 
>
>
> In fact, I cannot even use the DynamicCurrSquareSynapse that is 
> provided as an example. When I attempt to use it in a Python program, 
> for example, this:
>
> net = SingleThreadNetwork()
> inp_nrn = net.create(SpikingInputNeuron([some input spike times here]))
> syn = DynamicCurrSquareSynapse   # This runs.
> out_nrn = net.create(LifNeuron())
> net.connect(inp_nrn, out_nrn, syn) # Gives a runtime error.
>
> The error I consistently get from net.connect() is:
> Unidentifiable C++ exception
>
> Neurons I create with the extension module work correctly, however. I 
> experimented with creating different synapse types, and I only get 
> this error if the synapse is based off templates. So, for example, the 
> synapse I wanted to create was based off:
>
> GenericCurrentBasedSpikingSynase<ExponentialDecaySpikeResponse>
>
> and this synapse gives me the same unidentifiable C++ exception.
>
>
> If I don't use templates to create a synapse, then the synapse will 
> compile and not give any errors when I try to use it in a Python 
> script, however it doesn't seem to connect properly to the 
> postsynaptic neuron: it won't inject current into it. I've attached my 
> 'experimental' synapse type that I was using to test whether I could 
> get any synapse to work correctly (because any template-based synapse 
> gives me errors, I just copied code from the templates and created a 
> class that directly derives from ExponentialDecaySpikeResponse).
>
> Any ideas?
>
> Thanks,
> Nabeelah
>
>
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-- 
_______________________________________________
Dejan Pecevski
Institute for Theoretical Computer Science
Graz University of Technology
Inffeldgasse 16b, A-8010 Graz, Austria
Tel. +43 316 873 5849