Error when spawning an object

[cosi1]

Reproducible example:

Annotated7 <- R7::new_class("Annotated7",
  properties = list(
    metadata = "list"
  )
)
setClassUnion("DataFrame_OR_NULL7", "NULL")

Vector7 <- R7::new_class("Vector7",
  parent = Annotated7,
  properties = list(
    elementMetadata = "DataFrame_OR_NULL7"
  )
)
v <- Vector7()

# Error in do.call(base::`@`, list(object, name)) :
#   trying to get slot "parent" from an object of a basic class ("character") with no slots

A brief investigation revealed that when the parent constructor (constructor of Annotated7)
is run from the constructor of Vector7, it incorrectly interprets object_class(sys.function(-1))
as "function" (a character string) instead of an R7 class, and tries to access a slot of that string.
(The problem doesn't occur when the constructor of Annotated7 is executed directly.)
sys.function(-1) seems to be the culprit.

[hadley]

Possibly related to #72.

[hadley]

Revisit after #134 is merged.

[hadley]

With #134

library(R7)

Annotated7 <- new_class("Annotated7", properties = list(metadata = "list"))

union <- setClassUnion("DataFrame_OR_NULL7", "NULL")

Vector7 <- R7::new_class("Vector7",
  parent = Annotated7,
  properties = list(
    elementMetadata = union
  )
)
Vector7(metadata = list(), elementMetadata = NULL)
#> Error: <Vector7>@elementMetadata must be of class <DataFrame_OR_NULL7>, not NULL

^{Created on 2022-01-26 by the reprex package (v2.0.1)}

So this is just #72 + #139