This just means that R doesn't currently do anything complicated when you ask for a pointer to the data in an R vector object. But that doesn't matter; the behavior of REAL etc doesn't depend on that.
Note that INTEGER, REAL, etc just give you pointers of type int *, double *, etc. It's up to you to make sure that a particular use makes sense or you'll get garbage at best. As discussed in the manual, you can either do this on the R side, or in C: first check the type of the object, then coerce if that makes sense and is necessary, and handle errors as you see fit. Coercion between types requires a copy, in general, so you need to explicitly ask for that. Reid Huntsinger -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Faheem Mitha Sent: Monday, January 31, 2005 10:52 AM To: Prof Brian Ripley Cc: r-devel@stat.math.ethz.ch Subject: Re: [Rd] type of list elements in .Call On Mon, 31 Jan 2005, Prof Brian Ripley wrote: > This is covered, copiously, in the examples in `Writing R Extensions'. > Hint: search for coerceVector. I see. I thought that INTEGER and its relatives did coercion too, but now I see that is not stated anywhere. Eg. REAL is first used in "Writing R Extensions" in 4.7.1 as in REAL(ab)[0] = 123.45 ... and I cannot find a discussion about what it does previous to that, or indeed afterwards. In Rinternals header file, it says /* Under the generational allocator the data for vector nodes comes immediately after the node structure, so the data address is a known ofset from the node SEXP. */ This does not mean much to me. Perhaps a short comment in the documentation would be helpful, if not already present. Faheem. ______________________________________________ R-devel@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
