[R] S4 : setGeneric for classical methods

[cgenolin at u-paris10.fr]

Prof Brian Ripley <ripley at stats.ox.ac.uk> a écrit :

> On Tue, 22 Jul 2008, cgenolin at u-paris10.fr wrote:
>
>> Hi the list (well, half of the list, only the one who are not on 
>> holidays...)
>>
>> I am trying to make an S4 package. When I run it on a console, 
>> everything seems ok. When I run R CMD check, I got an error --- 8< 
>> ----------------------
>> Error in setMethod("plot", "ClassX", function(x, y) { :  no existing 
>> definition for function "plot"
>> --- 8< ----------------------
>>
>> If I add setGeneric("plot",function(x,y,...){standardGeneric("plot")})
>> in my code, then everything is OK.
>>
>> This is a surprise for me since I taught that we do not need to 
>> redefine as generic the function that are already generic, like 
>> "plot". Am I wrong ?
>
> Yes. And do read the error message.  It says
>
> 	no existing definition for function "plot"
>
> so this is not if the function is S3 or S4 generic, but that no such 
> function is visible.
>
> Looks like you forgot to declare a dependence on (or import) package 
> graphics.

I would have forgot if I knew that I have to declare such a dependence...
Do we have to declare all the depence to all the package ? To base ? To 
stats ? I thaught that the package that are include in R when we start 
it had not to be include.

Christophe