Laurent, On May 3, 2015, at 8:07 PM, Laurent Gautier <lgaut...@gmail.com> wrote:
> rPython appears to provide an interface from R to Python by embedding > Python and I'd think that it can safely assume that R has been initialized, > but might not be the point here. > > The issue is that a Python package embedding itself R (here rpy2) appears > to have no way to know that earlier in the life of the process R was > initialized. > Duncan's point was that it has - since it would have to embed R itself and thus record the initialization. I suppose you're asking about a case where you want to detect that something else already started R so you can't embed it yourself anymore and thus have to abort -- one side-effect check is to see if R_NilValue is NULL since that would only be the case if R was not started yet. Note, however, that if you didn't initialize it you can't embed it. Cheers, Simon PS: there are much better interfaces to Python than rPython (which is mostly dysfunctional) - see http://www.omegahat.org/RSPython https://github.com/s-u/rpython PPS: I wish you didn't hide the capsulling in rpy2 since that prevents us from having common references that rpy2 can use (please contact me off the list). > 2015-05-03 19:48 GMT-04:00 Duncan Murdoch <murdoch.dun...@gmail.com>: > >> On 03/05/2015 7:02 PM, Laurent Gautier wrote: >>> Beside the possible argumentation that with an API elegance and >>> convenience might sometimes be superior to necessity, the suggested >>> pattern ("every program, including R itself, keeping its own flag") does >>> no work too well when the nested embedding of R is involved. >>> >>> A concrete example is: >>> ``` >>> $ R -q >>>> library('rPython'); python.exec('import rpy2.robjects') >>> R is already initialized >>> ``` >> >> I don't know rPython at all, but surely this is an rPython bug. When >> the package is loaded by "library('rPython')", R is obviously >> initialized. You don't need to query it to ask that. >> >> The standard R front-ends don't need a flag to know if it is >> initialized. They initialize, then go into the read-eval-print loop. >> If they are in that loop, R is initialized. If it failed to initialize, >> they would never get to that loop. >> >> Other front-ends may do other things besides run R, so they do need to >> know if it is initialized, but surely they can keep a flag telling them >> whether they've succeeded in initializing it. >> >> Duncan Murdoch >> > > [[alternative HTML version deleted]] > > ______________________________________________ > 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
