Does the {.inheritable.} pragma convert an object into a pointer or keep it as
a normal object with copy semantics?
Also, something to bear in mind, upon testing this it seems the type is erased
when inserting into a seq: (Nim version 0.17.3 2017-10-13)
import typetraits
type
Obj1 = object {.inheritable.}
a: int
Obj2 = object of Obj1
b: float
var
x = newSeq[Obj1]()
x.add Obj1(a: 1)
x.add Obj2(a: 2, b: 3.5) # This is allowed
echo x[1].type.name # output Obj1, not Obj2
echo Obj2(x[1]) # This fails at run time with invalid object
conversion, Obj2's extra fields are lost
Should the compiler warn that putting an Obj2 into a seq of Obj1 will drop it's
extra data? Or is the extra data meant to be there but there's a bug somewhere?
With a ref, the type is obscured but internally preserved as expected:
import typetraits
type
ARef1 = ref object of RootObj
a: int
ARef2 = ref object of ARef1
b: float
var
y = newSeq[ARef1]()
y.add ARef1(a: 1)
y.add ARef2(a: 2, b: 4.5)
# output ARef1, not ARef2 (probably because 'type' is compiletime)
echo y[1].type.name
# displays data as ARef2 as expected, data is preserved - assuming you can
cast appropriately at runtime
echo ARef2(y[1]).repr
