R devel - Aug 2003 - S4 methods bug in naming of slots (PR#3665)

Hello,

I am using R 1.7.1 on a Redhat Linux machine, version 7.3.
The following works fine: 

setClass("ok", representation(
      "A"       = "matrix",
      "Cmatrix" = "matrix"))

new("ok",
    "A" = diag(4),
    "Cmatrix" = diag(4))

But the following doesn't work:

setClass("notok", representation(
      "A" = "matrix",
      "C" = "matrix"))

new("notok",
    "A" = diag(4),
    "C" = diag(4))

It says
> new("notok",
+    "A" = diag(4),
+    "C" = diag(4))
Error in methodsPackageMetaName("C", name) :
        The name of the object (e.g,. a class or generic function) to find in
the meta-data must be a single string (got an object of class
"matrix")

Can this bug be fixed? It doesn't work in the Windows version either. 
Thanks in advance.

Thomas

On Wed, Aug 06, 2003 at 06:26:53AM +0200, statwy@stat.nus.edu.sg
wrote:
> Hello,
> 
> I am using R 1.7.1 on a Redhat Linux machine, version 7.3.
> The following works fine: 
> 
> setClass("ok", representation(
>       "A"       = "matrix",
>       "Cmatrix" = "matrix"))
> 
> new("ok",
>     "A" = diag(4),
>     "Cmatrix" = diag(4))
> 
> But the following doesn't work:
> 
> setClass("notok", representation(
>       "A" = "matrix",
>       "C" = "matrix"))
> 
> new("notok",
>     "A" = diag(4),
>     "C" = diag(4))
> 
> It says
> 
> > new("notok",
> +    "A" = diag(4),
> +    "C" = diag(4))
> Error in methodsPackageMetaName("C", name) :
>         The name of the object (e.g,. a class or generic function) to find
in the meta-data must be a single string (got an object of class
"matrix")
> 
> Can this bug be fixed? It doesn't work in the Windows version either. 
> Thanks in advance.
 It is not really a bug. If you look at the definition of the function
 new you will see that its first argument is named Class. The argument
 you want to use for the C slot gets matched to the Class argument -
 it isn't a class and you get an error message. So, to avoid
 the partial matching algorithm for matching fucntions arguments you
 would need to go:
 
  new(Class="notok", A=diag(4), C=diag(4))

 which does work. Note also, no need for quotes around A and C.

 Robert

> 
> Thomas
> 
> ______________________________________________
> R-devel@stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-devel
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| Associate Professor              fax:   (617)  632-2444                   |
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