Orphaned TopologyParticle?

[mattwthompson]

There is a TopologyMolecule.particle method that attempts to return instances of TopologyParticle, which is never defined in the current codebase. ([Not tested], and that's probably for the better)

(openff-dev) [openforcefield] grep -R "class Topology" .                                                                                                       ci-lint  ✭ ✱
./openforcefield/topology/topology.py:class TopologyAtom(Serializable):
./openforcefield/topology/topology.py:class TopologyBond(Serializable):
./openforcefield/topology/topology.py:class TopologyVirtualSite(Serializable):
./openforcefield/topology/topology.py:class TopologyMolecule:
./openforcefield/topology/topology.py:class Topology(Serializable):
(openff-dev) [openforcefield] grep -R "class TopologyParticle" .                                                                                               ci-lint  ✭ ✱

My other guess, that it's something @trevorgokey is working on in #548, didn't bear any fruit.

There's some history (#233, #235) so I figure it may have just slipped through the cracks? I will remove this if there are not immediate plans for it.

[trevorgokey]

Thanks for pointing this out. Go ahead and leave it there; I will modify it to work with the virtual site PR (#548). I currently have a class TopologyVirtualParticle(TopologyVirtualSite) in the implementation, so a TopologyParticle seems intuitive to have (even though I never had to use this missing functionality).