search for: compact_intseq

Experimenting with altrep objects and v3 serialization, I discovered a possible bug. Calling DATAPTR on a compact_intseq object returns a pointer to the expanded integer sequence in memory. If you modify this data, the object values appear to be changed. However, if the compact_intseq object is then serialized (with version=3), only the original integer sequence info is written. For example, suppose I have compile...

...e fst package wraps an external C++ library (fstlib, independent from R) that was made for high speed serialization of dataframe's. Sequences are fairly common in dataframe's and I'm planning to add the concept of a sequence to the (R-agnostic) fst format. When I can detect, e.g. a 'compact_intseq' ALTREP vector and just retrieve it's 3 integer internal representation, serialization could be very fast. Alternatively, as you describe, the vector needs to be expanded first before serialization, which will actually be slower than using an already expanded vector and can take a lot of RA...

For now you can use R_altrep_inherits(x, R_compact_intseq_class) The variable R_compact_intseq_class should currently be visible to packages on all platforms, though that may change if we eventually provide a string-based lookup mechanism, e.g. somehting like R_find_altrep_class("compact_intseq", "base") Best, luke On Tue, 4 Jun...

thanks for clearing that up, so these methods are actually not meant to be exported on Windows and OSX? Some of the ALTREP methods that now use 'attribute_hidden' would be very useful to packages that aim to be ALTREP aware, should the currently (exported) API be considered final? thanks for your time & best, Mark On Tue, Jun 4, 2019 at 6:52 PM Tierney, Luke <luke-tierney at