[Rd] attach "warning" is a message

[Simon Urbanek]

Barry,

it is not a warning nor plain output, it is a message, so you can use 

> d = data.frame(x=1:10)
> x=1
> suppressMessages(attach(d))
>

Looking at the history, this used to be cat() but got changed to a message in R 3.2.0 (r65385, CCIng Martin in case he remembers the rationale for warning vs message). I don't know for sure why it is not a warning, but I can see that it is more in the line with informative messages (like package masking) as opposed to a warning - in fact the change suggest that the intention was to synchonize both. That said, I guess the two options are to clarify the documentation (also in library()) or change to a warning - not sure what the consequences of the latter would be.

Cheers,
Simon



> On 10/08/2021, at 2:06 AM, Barry Rowlingson <b.rowlingson using lancaster.ac.uk> wrote:
> 
> If I mask something via `attach`:
> 
>> d = data.frame(x=1:10)
>> x=1
>> attach(d)
> The following object is masked _by_ .GlobalEnv:
> 
>    x
>> 
> 
> I get that message. The documentation for `attach` uses the phrase
> "warnings", although the message isn't coming from `warning()`:
> 
> warn.conflicts: logical.  If ‘TRUE’, warnings are printed about
>          ‘conflicts’ from attaching the database, unless that database
>          contains an object ‘.conflicts.OK’.  A conflict is a function
>          masking a function, or a non-function masking a non-function.
> 
> and so you can't trap them with options(warn=...) and so on. This sent me
> briefly down the wrong track while trying to figure out why R was showing a
> masking error in one context but not another - I wondered if I'd supressed
> warning()s in the other context.
> 
> Personally I'd like these messages to be coming from warning() since that
> seems the appropriate way to warn someone they've done something which
> might have unwanted effects. But fixing the documentation to say "If
> ‘TRUE’, *messages* are printed" is probably less likely to break existing
> code.
> 
> Happy to add something to bugzilla if anyone thinks I'm not being overly
> pedantic here.
> 
> Barry
> 
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> 
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