On Mon, Mar 25, 2013 at 6:51 AM, Francisco J. Bido <b...@mac.com> wrote: > Hi, I'm new to OOP in R so please forgive the naiveness of some of the > questions. Here are a couple of them. It would be great if you can contrast > to OOP in Java.
Java is not the end-all of OOP (in fact S is a good bit older than Java) and you might find that the Lisp or Dylan object systems are a better analogy. (I'm only going by hearsay on Dylan; never used it myself) You might also quickly breeze through: https://github.com/hadley/devtools/wiki/S3 > > 1. R's S4 appears to centered around a dispatch mechanism which in my > understanding is just a way to implement polymorphism. Now, here's the snag, > I thought polymorphism was an aspect of OOP not by itself the definition of > OOP. What am I missing here? Is any language that implements polymorphism > automatically OO? > If you accept the immutability of objects, then arguably yes, I suppose polymorphism gives you a great deal of it. The remaining weaknesses are generally addressed by the S4 object system. (Not immutability of bindings like Haskell, but the fact that x <- y <- 1:5; y[3] <- 10 won't change x. In theory this is done by creating a new y with the modified 3rd element and binding the name y to that; not entirely thus in practice for performance reasons ) > 2. Can someone provide a simple example of how NextMethod() works? I read > some things about but I can't make any sense out of it. > It's supposed to facilitate inheritance but how? Why is it needed, what > happens if it's ignored? An example would be useful. Is there a Java > equivalent of NextMethod()? Grepping through R's source, it seems that the print system uses a fair amount of NextMethod for the AsIs and noquote print methods. You might take a look at those: also, section 7 of http://cran.r-project.org/doc/manuals/r-devel/R-exts.html MW > > Many Thanks! > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
