usually the alternative is a closure. But in your case, I would use:
type Fighter = object
phys: PhysicsComponent
proc update(f: var Fighter) = update(f.phys)
type Flyer = object
phys: PhysicsComponent
proc update(f: var Flyer) = update(f.phys)
var
flyers: seq[Flyer]
fighers: seq[Fighter]
for f in flyers: f.update
for f in fighers: f.update
You can use templates and macros to fight the boilerplate. For example, you can
use `macros.getType` in your update proc to iterate over the specific fields
and call the component specific update procs.
