[R] Get Slot from a Class

[Thomas Lumley]

On Thu, 20 May 2004, Yao, Minghua wrote:

> Hello, everyone,
>
> I don't quite understand the following message:
>
> > TTT <- t.test(1:10, y=c(7:20))
> > class(TTT)
> [1] "htest"
> > TTT at p.value
> Error: Trying to get slot "p.value" from an object whose class ("htest")
> is not defined
> > TTT$p.value
> [1] 1.855282e-05
>
> Why the message says the class of TTT is not defined while class(TTT)
> gets "htest"?

The classical tests use the S3 class system, not the S4 system.  They
don't have slots, and they don't have formal class representations (they
weren't created with setClass).

The message could perhaps be clearer, but it is saying that there is no
formal definition of a "htest" class and so you can't use the @ operator
on these objects.

	-thomas