[R] dumpClass, hasSlot in R?

[hadley wickham]

There are a few notes about difference between the R implementation
and the book at http://developer.r-project.org/methodsPackage.html

I found the hardest thing to get to grips in R was method calling -
using multiple dispatch (totally different to what I'm used to from
Java, Python etc.).  I found this tutorial
(http://www.gwydiondylan.org/gdref/tutorial.html, the sections on
generic functions and multiple-dispatch) very useful.  However, it is
for another programming language, and although the method and class
creation process feels very similar to R, the syntax is quite
different.  There is definitely scope for a similarly structured
introduction to S4 classes in R.

Hadley