set_obj_field.nim

import macros

type
  Container = object
    field1: string
    field2: string
    fieldInt: int

macro setField(obj: untyped, name: string, val: untyped): untyped =
  result = newStmtList()
  let field = parseExpr(name.strVal)
  result.add quote do:
    `obj`.`field` = `val`

var h: Container
echo h
# (field1: nil, field2: nil, fieldInt: 0)
h.setField("field1", "it works!")
echo h
# (field1: "it works!", field2: nil, fieldInt: 0)
h.setField("fieldInt", 120)
echo h
# (field1: "it works!", field2: nil, fieldInt: 120)