luke-tierney at uiowa.edu
2015-Jun-30 15:11 UTC
[Rd] Defining a `show` function breaks the print-ing of S4 object -- bug or expected?
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.duncan at 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-tierney at uiowa.edu Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
Lorenz, David
2015-Jun-30 15:27 UTC
[Rd] Defining a `show` function breaks the print-ing of S4 object -- bug or expected?
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: setMethod("show", "Person", function(object) { for an object of class "Person" for example. Dave On Tue, Jun 30, 2015 at 10:11 AM, <luke-tierney at 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.duncan at 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-tierney at uiowa.edu > Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu > > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel >[[alternative HTML version deleted]]
Duncan Murdoch
2015-Jun-30 15:33 UTC
[Rd] Defining a `show` function breaks the print-ing of S4 object -- bug or expected?
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. 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-tierney at 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.duncan at 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-tierney at uiowa.edu >> Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu >> >> >> ______________________________________________ >> R-devel at r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel >> > > [[alternative HTML version deleted]] > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel >
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