Trouble with custom serialization via serial_config()

[wlandau]

@shikokuchuo, thanks for introducing serial_config(). I am eager to build it into crew, but I am having trouble using it correctly. In the small test below, the (un)serialization functions do not seem to run. What am I missing?

In addition, what should I write for the class argument of serial_config() if I want to serialize every object? If the mechanism is S3-based, would class = "default" work? I'm thinking about sfunc = qs2::qs_serialize and ufunc = qs2::qs_deserialize.

library(mirai)

daemons(
  n = 1,
  serial = mirai::serial_config(
    class = "custom",
    sfunc = function(x) serialize("serialization successful", NULL),
    ufunc = unserialize
  )
)
#> [1] 1

task <- mirai(object, object = structure(list("a"), class = "custom"))
call_mirai(task)

# I expect "serialization successful".
print(task$data)
#> [[1]]
#> [1] "a"
#> 
#> attr(,"class")
#> [1] "custom"

daemons(n = 0)
#> [1] 0

^{Created on 2025-03-27 with reprex v2.1.1}

Session info

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[wlandau]

Incidentally, the torch example at https://shikokuchuo.net/mirai/articles/torch.html works just fine on my end.

[shikokuchuo]

The refhooks only work on "non-system reference objects", this being a term in base R. So your list with a custom class won't work. A classed environment would.

End of the day, if it's about qs2 support, that's coming, but at a lower level so you'll get more of the benefit than trying to do that using the hooks.