The public connection API is defined in https://github.com/wch/r-source/blob/trunk/src/include/R_ext/Connections.h
I'm not sure of a good pedagogic example; people who want to write their own connections usually want to do so for complicated reasons! This is my own abandoned attempt https://github.com/mtmorgan/socketeer/blob/b0a1448191fe5f79a3f09d1f939e1e235a22cf11/src/connection.c#L169-L192 where connection_local_client() is called from R and _connection_local() creates and populates the appropriate structure. Probably I have done things totally wrong (e.g., by not checking the version of the API, as advised in the header file!) Martin Morgan On 5/6/20, 2:26 PM, "R-devel on behalf of Duncan Murdoch" <r-devel-boun...@r-project.org on behalf of murdoch.dun...@gmail.com> wrote: On 06/05/2020 1:09 p.m., frede...@ofb.net wrote: > Dear R Devel, > > Since Linux moved away from using a file-system interface for audio, I think it is necessary to write special libraries to interface with audio hardware from various languages on Linux. > > In R, it seems like the appropriate datatype for a `snd_pcm_t` handle pointing to an open ALSA source or sink would be a "connection". Connection types are already defined in R for "file", "url", "pipe", "fifo", "socketConnection", etc. > > Is there a tutorial or an example package where a new type of connection is defined, so that I can see how to do this properly in a package? > > I can see from the R source that, for example, `do_gzfile` is defined in `connections.c` and referenced in `names.c`. However, I thought I should ask here first in case there is a better place to start, than trying to copy this code. > > I only want an object that I can use `readBin` and `writeBin` on, to read and write audio data using e.g. `snd_pcm_writei` which is part of the `alsa-lib` package. I don't think R supports user-defined connections, but probably writing readBin and writeBin equivalents specific to your library wouldn't be any harder than creating a connection. For those, you will probably want to work with an "external pointer" (see Writing R Extensions). Rcpp probably has support for these if you're working in C++. Duncan Murdoch ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
