[R] Question about S4

[Hun S. Tesatte]

PS. All class names were upper-case, I messed up while copying the 
code, but it has no effect on the result. Thanks for help.

--Hun


On Mon, 23 Nov 2009 10:28:37 +0100 "Hun S. Tesatte" 
<hunsyntesat at hush.com> wrote:
>Dear R-ers,
>
>I don't understand the following, maybe someone will help me 
>explain:
>
>> setClasss('A')
>[1] "A"
>> new('a')
>Error in new("a") : 
>  trying to generate an object from a virtual class ("a")
>
>> setClass('b', contains='a')
>[1] "b"
>> new('b')
>An object of class “b”
><S4 Type Object>
>
>In what way is B more concrete than A so that it's possible do 
>instantiate B but not A? I don't quite get it. B adds nothing to 
>nothing, and yet it's instantiable, while it's base is not. Makes 
>no sense to me.
>
>-- Hun