On Friday, 7 July 2023 at 20:33:08 UTC, bachmeier wrote:
[snip]
I was wrong. They added custom allocators a while back, but
didn't tell anyone.
Actually, what I said before is technically correct. The SEXP
struct itself still has to be allocated by R and managed by the
R garbage collector. It's just that you can use a custom
allocator to send a pointer to the data you've allocated, and
once R is done with the data, it'll call the function you've
provide to free the memory before destroying the SEXP struct
that wraps it.
I uploaded [an example
here](https://github.com/bachmeil/betterr/blob/main/testing/testalloc.d).
It's still a bit hackish because you need to adjust the pointer
for a header R inserts when it allocates arrays. Adjusting by
10*double.sizeof works in this example, but "my test didn't
segfault" doesn't exactly inspire confidence. Once I am
comfortable with this solution, I'll do a new release of
betterr.
This'll be kind of a big deal if it works. For instance, if you
want to use a database interface and D doesn't have one, you
can use R's interface to that database without having R manage
your project's memory. You could use any of the available R
interfaces (databases, machine learning libraries, Qt, etc.)
Cool.
The main thing I want to try is rstan. They have an interface
called cmdstan that you can call from the command line that would
be possible to use with D. The problem is that you have to write
the data to a CSV file and then read it. So it would be kind of
slow and I never got around to playing around with it in D. With
your tool as it is, I would just have to copy the data in memory,
which I would expect not to be as bad of an overhead as IO (but
again haven't gotten around to do anything with it).
