[Rd] Simple class with an automatic printing issue

[Tom Short]

Thanks, Bill. Searching R-devel based on your input shows that this is
a known issue as pointed out by Martin Maechler:

https://stat.ethz.ch/pipermail/r-devel/2008-October/051109.html

- Tom



On Sun, Apr 12, 2009 at 11:34 PM, William Dunlap <wdunlap at tibco.com> wrote:
>
> It may have to do with the results of is.object():
>
>  > is.object(1*structure(1,class="testClass"))
>  [1] FALSE
>  > is.object(structure(1,class="testClass")*1)
>  [1] TRUE
>  > is.object(structure(1,class="testClass"))
>  [1] TRUE
>
> is.object(x) should be true if x has a class attribute,
> but 1*structute(1,class="testClass") makes a thing
> with a class attribute but without the 'OBJECT' bit set.
>
> Bill Dunlap
> TIBCO Software Inc - Spotfire Division
> wdunlap tibco.com
>
> > -----Original Message-----
> > From: r-devel-bounces at r-project.org
> > [mailto:r-devel-bounces at r-project.org] On Behalf Of Tom Short
> > Sent: Sunday, April 12, 2009 4:00 PM
> > To: r-devel at r-project.org
> > Subject: [Rd] Simple class with an automatic printing issue
> >
> > I don't understand the following behavior for a simple S3 class. The
> > auto-printing at the command line
> > doesn't behave as I expect. I'm probably missing something,
> > but it might be
> > a bug.
> >
> > > print.testClass <- function(x, ...) cat("Class:", class(x),
> > ":", x, "\n")
> >
> > > structure(1, class = "testClass")
> > Class: testClass : 1
> >
> > > print(1 * structure(1, class = "testClass"))
> > Class: testClass : 1
> >
> > > 1 * structure(1, class = "testClass") # why doesn't
> > auto-printing call
> > print.testClass here?
> > [1] 1
> > attr(,"class")
> > [1] "testClass"
> >
> > > structure(1, class = "testClass") * 1
> > Class: testClass : 1
> >
> >
> > platform       i386-pc-mingw32
> > arch           i386
> > os             mingw32
> > system         i386, mingw32
> > status         RC
> > major          2
> > minor          9.0
> > year           2009
> > month          04
> > day            10
> > svn rev        48318
> > language       R
> > version.string R version 2.9.0 RC (2009-04-10 r48318)
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >