Any conceptual opposition to renaming

optionable_rule

to

subsystem_rule

? The only time we use it is when registering a Subsystem with the engine — I don’t think we need the flexibility that comes with

Optionable

The first time I read

optionable_rule

, I mistook it for

optional_rule

, which confused me. Likewise,

Subsystem

is a more concrete concept than

Optionable

I've never liked

optionable_rule

as a name. this strikes me as a good change

what if we develop a new concept that’s still an Optionable and want to phase out Subsystem? do we want to require people to then change all their own pants plugins? this seems like a matter of lacking documentation for pants’s incredible options system and i’m not sure i fully understand what this buys us.

I think the main problem is that "optionable" is a confusing word. we could change that to something else that is still more general than subsystems

in general, i’m a little concerned about changes made in the name of simplifying concepts. making this change seems to add more churn in the v2 engine which unsettled me as we try to make the v2 api more palatable for real use cases.