[Rd] Help for methods

Gabor Grothendieck ggrothendieck at gmail.com
Tue Sep 19 15:12:42 CEST 2006

On my system all three of the ?summary commands listed in your
post bring up help (if you add the missing parenthesis to the middle one).

I am using "Version 2.3.1 Patched (2006-06-04 r38279)" on Windows XP.

On 9/18/06, hadley wickham <h.wickham at gmail.com> wrote:
> Help for help says:
> The 'topic' argument may also be a function call, to ask for
>          documentation on a corresponding method.  See the section on
>          method documentation.
> and
>     The authors of formal ('S4') methods can provide documentation on
>     specific methods, as well as overall documentation on the methods
>     of a particular function.  The '"?"' operator allows access to
>     this documentation in three ways.
> ...
>     There are two different ways to look for documentation on a
>     particular method.  The first is to supply the 'topic' argument in
>     the form of a function call, omitting the 'type' argument. The
>     effect is to look for documentation on the method that would be
>     used if this function call were actually evaluated. See the
>     examples below.  If the function is not a generic (no S4 methods
>     are defined for it), the help reverts to documentation on the
>     function name.
> Which doesn't explicitly mention whether this will work for S3 either
> way, but the results from:
> ?summary
> ?summary(lm(wt ~ mpg, data=mtcars)
> ?summary(data.frame())
> seem to indicate that it doesn't (at least in my R2.3.0, which is out
> of date, but I did also search the latest NEWS file for anthing
> mentioning help).  Would it be possible to extend this method to deal
> with S3 classes as well?
> Hadley
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