R devel - Feb 2010 - How S3method() is implemented and called? And when to use it?

R-exts.pdf discribes S3method a little bit. But I want to understand
more on how it is called, implemented and when to use it.

I don't find it in an R session. But I see S3method() in some NAMESPACE
files.
> S3method
Error: object 'S3method' not found
> ?S3method
No documentation for 'S3method' in specified packages and libraries:
you could try '??S3method'



I don't understand why S3method is necessary.

My understanding is that we can always use
print.foo(<something) {<function body>} # and appropriate exporting
to replace
S3method(print, foo)
, right?

Or I misunderstand something?

Hello `Blue Sky` ,

Will you please start posting under your real name.

As documented in WRE, S3method is meant for use in namespaces:
http://cran.r-project.org/doc/manuals/R-exts.html#Registering-S3-methods

It is not an R function.

Romain

On 02/14/2010 07:32 PM, blue sky wrote:
>
> R-exts.pdf discribes S3method a little bit. But I want to understand
> more on how it is called, implemented and when to use it.
>
> I don't find it in an R session. But I see S3method() in some NAMESPACE
files.
>
>> S3method
> Error: object 'S3method' not found
>> ?S3method
> No documentation for 'S3method' in specified packages and
libraries:
> you could try '??S3method'
>
>
>
> I don't understand why S3method is necessary.
>
> My understanding is that we can always use
> print.foo(<something) {<function body>} # and appropriate
exporting
> to replace
> S3method(print, foo)
> , right?
>
> Or I misunderstand something?

-- 
Romain Francois
Professional R Enthusiast
+33(0) 6 28 91 30 30
http://romainfrancois.blog.free.fr
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