[Gretl-users] Re: foreign block: no printouts from R

On Sat, Jul 9, 2022 at 3:25 PM Sven Schreiber <svetosch(a)gmx.net&gt; wrote: > > Am 09.07.2022 um 12:22 schrieb Riccardo (Jack) Lucchetti: >> On Fri, 8 Jul 2022, Sven Schreiber wrote: >> >>> Hi all, >>> >>> I'm currently using the foreign block and specialized (user-defined) R >>> functions a bit more seriously. I'm noticing that the output from >>> print() calls inside the R functions does not seem to make it to the >>> outside. Consider the following minimal example: >> >> [...] >> >> An update on this. Allin and I spent some time trying to track the >> problem down, and we now think that this has something to do with the >> way we internally use the R shared library. >> >> The problem is, finding the documentation for that has proven to be a >> bit of a struggle. We'll see what we can do. >> > > Thanks, Allin and Jack! So it doesn't seem to be a Windows-only issue. > If it's not fixable in the short term, I'd suggest to just create a bug > tracker ticket and postpone the fix, since it doesn't seem very urgent > to me. I thought I'd replied to this before, but somehow my message didn't get sent. Anyway, here's the story. When we're calling R in the usual foreign-block setting we're sending R (binary or library, it doesn't matter) some lines of R script. In that case it's easy to insert some "sink()" statements to control where the output goes, so that gretl can collect it. But if you call a previously defined R function via gretl we're not sending any script, the transaction takes place entirely via the libR API. There's no obvious way to control where any R output goes, and in fact it goes automatically to stdout (evident if you run Sven's test script in such a way that you can see stdout, e.g. from the command line in a terminal window). Jack and I tried searching the R documentation for a means of controlling text output via the library API but we didn't find anything yet. Some of the third-party libraries that gretl uses offer a way of supplying a replacement for the standard C function printf() -- e.g. libxml, libcurl -- but we can't find anything of that sort in the libR API.