Error when inheriting in python

Question

I'm using a not-well-known framework called IPKISS; hopefully, this does not matter.

from ipkiss.all import *    

class ElectrodePair(Structure):
    """An electrode component to be used for a PPLN design."""

    __name_prefix__ = "ELECTRODE_PAIR"

    width = PositiveNumberProperty(required = True)
    height = PositiveNumberProperty(required = True)
    seperation = PositiveNumberProperty(required = True)

    lay1 = Layer(number = 1, name = "boundaries")

    def define_elements(self, elems):
        left = ShapeRectangle(center = (-self.seperation*0.5,0.), box_size = (self.width, self.height))
        right = ShapeRectangle(center = (self.seperation*0.5,0.), box_size = (self.width, self.height)) 

        elems += Boundary(layer = self.lay1, shape = left)
        elems += Boundary(layer = self.lay1, shape = right)
        return elems



class ElectrodeStructure(ElectrodePair):
    """An array of electrodes."""

    __name_prefix__ = "ELECTRODE_STRUCTURE"

    amount = PositiveNumberProperty(required = True)
    spacing = PositiveNumberProperty(required = True)

    def define_elements(self, elems):
        electrodePair = ElectrodePair.__init__(self)
        elems += ARefX(reference = electrodePair, origin = (0,0), period_1d = self.spacing, n_o_periods_1d = self.amount)
        return elems



def main():
    FILE_NAME = "ElectrodeArray.gds"
    electrodeArray = ElectrodeStructure(amount = 10, height = 100., seperation = 20, spacing = 10., width = 2.)

    electrodeArray.write_gdsii(FILE_NAME)


if __name__ == "__main__":
    main()

I have no idea why this is erroring. The error is:

File "/usr/local/lib/python2.7/dist-packages/IPKISS-2.4_ce-py2.7.egg/ipcore/properties/initializer.py",
line 327, in __init__ raise IpcoreAttributeException("Required property '%s' is not found in keyword arguments of '%s' initialization." % (p, str(type(self))))
ipcore.exceptions.exc.IpcoreAttributeException: Required property 'amount' is not found in keyword arguments of '<class '__main__.ElectrodeStructure'>' initialization.

It seems as though it's not happy with how I've passed my arguments, I've tried heaps of stuff and cannot get it to work. Advice would be much appreciated.

I suspect the error is due to electrodePair = ElectrodePair.__init__(self).

Thank you for your time.

Yes, you must specify an amount in your ElectrodePair initializer — hd1
– hd1, Commented Jan 7, 2014 at 7:01

volcano · Accepted Answer · 2014-01-07 07:20:49Z

1

You have to add __init__ method to your ElectrodeStructure class, that - as @hd1 has pointed out - has to set amount:

class ElectrodeStructure(ElectrodePair):
    def __init__(self, amount):
        ElectrodePair.__init__(self)

The way you call ElectrodePair.__init__ is wrong, since in the absence of ElectrodeStructure.__init__ in your class the former will be called automatically

EDIT:

Couple of things I've noticed on re-reading - you inherit from a class, and then within a class method you create an object of the parent class. Something is wrong here

edited Jan 7, 2014 at 7:20

answered Jan 7, 2014 at 7:09

volcano

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Comments

Seth · Accepted Answer · 2014-01-07 07:26:35Z

class ElectrodeStructure(ElectrodePair):
    [...]

    def define_elements(self, elems):
        electrodePair = ElectrodePair.__init__(self)
        [...]

When you create a new ElectrodeStructure in main(), you're passing keword arguments. Becuase you're not defining an __init__ function in ElectrodeStructure, the super's __init__ is being called with those arguments (including amount, so there's no error).

Then in define_elements, you're calling __init__ again, except you aren't passing in any arguments, which is causing the error.

Additionally, this statement:

        electrodePair = ElectrodePair.__init__(self)

Is assigning the return value (likely None) of ElectrodePair.__init__(self) to electrodePair. I suspect you want something more like the following:

        electrodePair = ElectrodePair(amount=1, etc.)

It looks like you want composition, not inheritance; you could initialize your subclass in a proper __init__ function (as @volcano describes), or just create an ElectrodePair class member, and not inherit at all.

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