question about assignment warnings for replacement methods
On Apr 8, 2011, at 2:55 PM, Herv? Pag?s wrote:
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
with
\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?
They are not equivalent (you can't use = in many places where you can use <-). Also my understanding is that it is considered bad practice by some to use = as assignment outside of the command prompt (interactive use) -- but opinions vary and I don't want to start a flame war here ;). Cheers, Simon
Thanks! H.
(though the manual suggests using the S3 style, I'm not sure how literally to take it). Duncan Murdoch
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