From Bill.Venables at csiro.au  Wed May 18 01:32:06 2011
From: Bill.Venables at csiro.au (Bill.Venables at csiro.au)
Date: Wed, 18 May 2011 09:32:06 +1000
Subject: [Rd] S3 method dispatch - can methods come from the enclosing
 environment?
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Message-ID: <1BDAE2969943D540934EE8B4EF68F95FE49C204ED8@EXNSW-MBX03.nexus.csiro.au>

I was surprised to see that S3 methods are not found if they only reside in the enclosing environment.  E.g.:

> tstFn <- local({
+   print.tst <- function(x, ...) cat("found it!")
+ 
+   function(x) print(x)
+ })
> 
> z <- "The cat sat on the mat."
> class(x) <- "tst"
> 
> tstFn(z)
[1] "The cat sat on the mat."
> 

So the answer to the question posed in the subject line is apparently "no". Perhaps this is well known and fully documented somewhere, but if so it has eluded me.  Is there some reason for this?  

I'm not sure if this is a bug, a feature, or a proposal for development, but I would welcome people's views on this curious little issue.

Bill Venables.


[Rd] S3 method dispatch - can methods come from the enclosing environment?
Bill.Venables at csiro.au