This fixed in R-devel in r68702; in R-3-2-branch in r68705.
Best,
luke
On Tue, 30 Jun 2015, Duncan Murdoch wrote:
On 30/06/2015 7:04 PM, Paul Gilbert wrote:
On 06/30/2015 11:33 AM, Duncan Murdoch wrote:
On 30/06/2015 5:27 PM, Lorenz, David wrote:
There is something I'm really missing here. The function show is a
standardGeneric function, so the correct way to write it as method like
this:
That describes methods::show. The problem is that the default print
mechanism isn't calling methods::show() (or base::print() as Luke says),
it's calling show() or print() in the global environment, so the user's
function overrides the generic, and you get the error.
These are two different problems aren't they? I can see that you might
want to ensure that base::print() calls methods::show(), but forcing the
default print to go to base::print(), rather than whatever print() is
first on the search path, would seem like a real change of philosophy.
What about all the other base functions that can be overridden by
something in the global environment?
I'd guess it's a minority of R users who know that print() or show() is
being called when you just evaluate an expression. Most would think R
just shows you the value of the expression. That's why they'd be
surprised when their local function suddenly stops the display of
variables from working.
On the other hand, if someone defined a print or show *method* in the
global environment, I think that one should override one defined in a
package namespace. It does now, and I wouldn't change that. The
difference is that I'd expect someone defining a method to know what
they're doing, but just defining a function doesn't imply that.
Duncan Murdoch
Paul
Luke, are you going to look at this, or should I?
Duncan Murdoch
setMethod("show", "Person", function(object) {
for an object of class "Person" for example.
Dave
On Tue, Jun 30, 2015 at 10:11 AM, <luke-tier...@uiowa.edu> wrote:
Same thing happens with S3 if you redefine print(). I thought that
code was actually calculating the function to call rather than the
symbol to use, but apparently not. Shouldn't be too hard to fix.
luke
On Tue, 30 Jun 2015, Hadley Wickham wrote:
On Tue, Jun 30, 2015 at 2:20 PM, Duncan Murdoch
<murdoch.dun...@gmail.com> wrote:
On 30/06/2015 1:57 PM, Hadley Wickham wrote:
A slightly simpler formulation of the problem is:
show <- function(...) stop("My show!")
methods::setClass("Person", slots = list(name = "character"))
methods::new("Person", name = "Tom")
#> Error in (function (...) : My show!
Just to be clear: the complaint is that the auto-called show() is not
methods::show? I.e. after
x <- methods::new("Person", name = "Tom")
you would expect
show(x)
to give the error, but not
x
??
Correct - I'd expect print() to always call methods::show(), not
whatever show() is first on the search path.
Hadley
--
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa Phone: 319-335-3386
Department of Statistics and Fax: 319-335-3017
Actuarial Science
241 Schaeffer Hall email: luke-tier...@uiowa.edu
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
[[alternative HTML version deleted]]
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
--
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa Phone: 319-335-3386
Department of Statistics and Fax: 319-335-3017
Actuarial Science
241 Schaeffer Hall email: luke-tier...@uiowa.edu
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
