Re: [Rd] question about assignment warnings for replacement methods

From: Hervé Pagès <>
Date: Fri, 08 Apr 2011 11:55:58 -0700

ink1">Hi Duncan, Marc,

On 11-04-05 11:15 AM, Duncan Murdoch wrote:
> On 05/04/2011 1:51 PM, Marc Carlson wrote:
>> Hi,
>> I have seen several packages that with the most recent version of R are
>> giving a warning like this:
>> Assignments in \usage in documentation object 'marginalData-methods':
>> marginalData(object) = value
>> I assume that this is to prevent people from making assignments in their
>> usage statements (which seems completely understandable). But what
>> about the case above? This is a person who just wants to show the
>> proper usage for a replacement method. IOW they just want to write
>> something that looks like what you actually do when you use a
>> replacement method. They just want to show users how to do something
>> like this:
>> replacementMethod(object)<- newValue
>> So is that really something that should not be allowed in a usage
>> statement?
> If replacementMethod was a replacement function, then
> replacementMethod(object)<- newValue
> is supposed to be fine.

Yes, 'replacementMethod(object) <- newValue' vorks indeed, but not 'replacementMethod(object) = newValue'.

> But if it is an S3 method, it should be
> \method{replacementMethod}{class}(object)<- newValue
> and if it is an S4 method I think it should be
> \S4method{replacementMethod}{signature_list}(object)<- newValue

In the case reported by Marc, replacementMethod was both: a replacement (generic) function and a replacement method. And the man page had an alias for both. Marc replaced

   replacementMethod(object) = newValue


   \S4method{replacementMethod}{signature_list}(object)<- newValue

and that solved the problem. But replacing '=' with '<-' solves it too.

Shouldn't 'R CMD check' treat the 2 assignment operators the same way since they are equivalent?


> (though the manual suggests using the S3 style, I'm not sure how
> literally to take it).
> Duncan Murdoch
> ______________________________________________
> mailing list

Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M2-B876
P.O. Box 19024
Seattle, WA 98109-1024

Phone:  (206) 667-5791
Fax:    (206) 667-1319

______________________________________________ mailing list
Received on Fri 08 Apr 2011 - 18:58:38 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Fri 08 Apr 2011 - 20:50:42 GMT.

Mailing list information is available at Please read the posting guide before posting to the list.

list of date sections of archive