S4 dispatch and S3 "connection" objects

We should probably incorporate this information in the pre-defined S4
versions of the classes, since these are basic S3 classes.

Anybody see a
down side?

Meanwhile, your approach is a reasonable workaround.

John

Michael Lawrence wrote:

On Mon, Dec 14, 2009 at 11:36 PM, Romain Francois<
romain.francois at dbmail.com>  wrote:

Hello,

I'm trying to get S4 dispatch on S3 "connection" objects.

So I do :

setOldClass( "connection" )

and then :

setGeneric( "bling", function(object) standardGeneric( "bling" ) )
setMethod( "bling", "connection", function(object) cat( "gotcha ",
as.integer(object), "\n" ) )

but I get :

f<- file( "blabla", open = "rb" )

bling( f )

Error in function (classes, fdef, mtable)  :
  unable to find an inherited method for function "bling", for signature
"file"

class( f )

[1] "file"       "connection"


Am I supposed to do :

setOldClass( c("file", "connection" ) )
setOldClass( c("url", "connection" ) )

and so on for each potential S3 class, or is there another way.

That's the way I've always done it.

Michael

Romain