import tables
import macros

type
  UIWidget = object
    test: int
  UICustom = proc(widget: UIWidget): NimNode

static:
  var custom: Table[string, proc(): UICustom]
  custom = initTable[string, proc(): UICustom]()

macro registerCustom(creator: static[proc(): UICustom]): untyped =
  result = newStmtList()
  custom["Hello"] = creator

proc myType(): UICustom {.compileTime.} =
  result = (proc(widget: UIWidget): NimNode =
    newStmtList()
  )

registerCustom(myType)