r-s3

If I a have a class called foo , then it is straightforward to overload the summary function summary.foo = function(x, ...) print("bar") However this technique does not work with the sd function, that is > bar = createFooClass() > sd.foo = function(x, ...) print("Hi") > sd(bar) error: is.atomic(x) is not TRUE What is the correct way of overloading this function? You can hijack any non-generic function, make it (S3) generic and set the original version to be the default version. For example: ## make an S3 generic for sd sd <- function(x, ...) UseMethod("sd") ## take the usual definition of sd,

Since I am fairly new to R, I do not know what the S3 methods and objects are. I found that there are S3 and S4 object systems, and some recommend to use S3 over S4 if possible (http://google-styleguide.googlecode.com/svn/trunk/google-r-style.html). However, I do not know the exact definition of S3 methods/objects. Most of the relevant information can be found by looking at ?S3 or ?UseMethod , but in a nutshell: S3 refers to a scheme of method dispatching. If you've used R for a while, you'll notice that there are print , predict and summary methods for a lot of different kinds of objects. In