From: John Chambers <jmc_at_r-project.org>

Date: Sat 23 Sep 2006 - 13:35:34 GMT

R-devel@r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-devel Received on Sat Sep 23 23:38:26 2006

Date: Sat 23 Sep 2006 - 13:35:34 GMT

Probably a bug, but not at all the one you imply. You have found a way to subvert a guarantee in R that methods for primitives can never be redefined for basic data types.

Parlamis Franklin wrote:

> i think these two code snippets exhibit a bug. they are identical

*> but for the inclusion of an initial line in snippet [2]
**>
**> [1]
**> setMethod("Math", signature(x = "numeric"), function(x) "Works")
**> getGeneric("sqrt")(4)
**>
**> [2]
**> getGeneric("sqrt")(4)
**> setMethod("Math", signature(x = "numeric"), function(x) "Works")
**> getGeneric("sqrt")(4)
**>
**> these are my results, when each is run from a fresh R session
**>
**> [1]
**> > setMethod("Math", signature(x = "numeric"), function(x) "Works")
**> [1] "Math"
**> > getGeneric("sqrt")(4)
**> [1] "Works"
**>
**> [2]
**> > getGeneric("sqrt")(4)
**> `__Deferred_Default_Marker__`
**> > setMethod("Math", signature(x = "numeric"), function(x) "Works")
**> [1] "Math"
**> > getGeneric("sqrt")(4)
**> `__Deferred_Default_Marker__`
**>
**> the section in "How Methods Work" that deals with this is unfinished,
**> but i think it suggests that getGeneric("sqrt")(4) should work out of
**> the box.
**>
**> franklin parlamis
**>
**> > version
**> _
**> platform powerpc-apple-darwin8.7.0
**> arch powerpc
**> os darwin8.7.0
**> system powerpc, darwin8.7.0
**> status beta
**> major 2
**> minor 4.0
**> year 2006
**> month 09
**> day 22
**> svn rev 39471
**> language R
**> version.string R version 2.4.0 beta (2006-09-22 r39471)
**>
**> ______________________________________________
**> R-devel@r-project.org mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-devel
**>
**>
*

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https://stat.ethz.ch/mailman/listinfo/r-devel Received on Sat Sep 23 23:38:26 2006

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