Class DftObj

python/simulation.py:627–684

Wrapper around DFT objects that allows delayed initialization of the structure. When splitting the structure into chunks for parallel simulations, we want to know all of the details of the simulation in order to ensure that each processor gets a similar amount of work. The problem with

class DftObj:
    """Wrapper around DFT objects that allows delayed initialization of the structure.

    When splitting the structure into chunks for parallel simulations, we want to know all
    of the details of the simulation in order to ensure that each processor gets a similar
    amount of work. The problem with DFTs is that the `add_flux` style methods immediately
    initialize the structure and fields. So, if the user adds multiple DFT objects to the
    simulation, the load balancing code only knows about the first one and can't split the
    work up nicely. To circumvent this, we delay the execution of the `add_flux` methods
    as late as possible. When `add_flux` (or `add_near2far`, etc.) is called, we:

    1. Create an instance of the appropriate subclass of `DftObj` (`DftForce`, `DftFlux`, etc.).
       Set its args property to the list of arguments passed to `add_flux`, and set its func
       property to the 'real' `add_flux`, which is prefixed by an underscore.

    2. Add this `DftObj` to the list Simulation.dft_objects. When we actually run the
       simulation, we call `Simulation._evaluate_dft_objects`, which calls `dft.func(*args)`
       for each dft in the list.

    If the user tries to access a property or call a function on the `DftObj` before
    `Simulation._evaluate_dft_objects` is called, then we initialize the C++ object through
    swigobj_attr and return the property they requested.
    """

    def __init__(self, func, args):
        """Construct a `DftObj`."""
        self.func = func
        self.args = args
        self.swigobj = None

    def swigobj_attr(self, attr):
        if self.swigobj is None:
            self.swigobj = self.func(*self.args)
        return getattr(self.swigobj, attr)

    @property
    def save_hdf5(self):
        return self.swigobj_attr("save_hdf5")

    @property
    def load_hdf5(self):
        return self.swigobj_attr("load_hdf5")

    @property
    def scale_dfts(self):
        return self.swigobj_attr("scale_dfts")

    @property
    def remove(self):
        return self.swigobj_attr("remove")

    @property
    def freq(self):
        return self.swigobj_attr("freq")

    @property
    def where(self):
        return self.swigobj_attr("where")