Is there any way to check the class of an ALTREP?

You happened to send a link which points to the OP's own package :) I
think Jiefei would like to know how one can "officially" determine if an
arbitrary ALTERP object belongs to a class that he owns.

Benjamin,

You happened to send a link which points to the OP's own package :) I
think Jiefei would like to know how one can "officially" determine if an
arbitrary ALTERP object belongs to a class that he owns.

Regards,
Denes


On 10/19/20 10:22 AM, Benjamin Christoffersen wrote:

It seems as if you can you use the ALTREP macro as done in this
package: https://github.com/Jiefei-Wang/SharedObject/blob/804b6ac58c63a4bae95343ab43e8b1547b07ee6b/src/C_interface.cpp#L185

and in base R: https://github.com/wch/r-source/blob/54fbdca9d3fc63437d9e697f442d32732fb4f443/src/include/Rinlinedfuns.h#L118

The macro is defined here in Rinternals.h:
https://github.com/wch/r-source/blob/abb550c99b3927e5fc03d12f1a8e7593fddc04d2/src/include/Rinternals.h#L325

Den man. 19. okt. 2020 kl. 10.13 skrev Jiefei Wang <szwjf08 at gmail.com>:

Hi all,

I would like to determine if an ALTREP object is from my package, I see
there is a function `ALTREP_CLASS` defined in RInternal.h but its return
value is neither a `R_altrep_class_t` object nor an STRSXP representing a
class name. I do not know how to correctly use it. Any suggestions?

Thanks,
Jiefei

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