[Rd] Inconsistency in as.data.frame.table for stringsAsFactors

[hadley wickham]

On Fri, Jan 22, 2010 at 2:17 AM, Martin Maechler
<maechler at stat.math.ethz.ch> wrote:
>>>>>> "SM" == Stavros Macrakis <macrakis at alum.mit.edu>
>>>>>>     on Thu, 21 Jan 2010 20:19:28 -0500 writes:
>
>    SM> I noticed that in as.data.frame.table, the stringsAsFactors argument
>    SM> defaults to TRUE, whereas in the other as.data.frame methods, it defaults to
>    SM> default.stringsAsFactors().
>
>    SM> The documentation and implementation agree on this, so this is not a bug.
>
>    SM> However, I was wondering if this disparity was intended or if it might be
>    SM> some sort of unintentional oversight.  If it is intentional, I wonder what
>    SM> the rationale is.
>
> Some of us (including me) have strongly argued on several
> occasions that  global options() settings should *not* have an effect
> on anything "computing" but just on "output"
> i.e. printing/graphing of R results.
> As it is currently, potentially R scripts and R functions may
> only work correctly for one setting of
>     options( stringsAsFactors = * )
> which is against all principles of functional programming.

A similar argument would also seem to apply to defaultPackages,
deparse.max.lines, download.file.method, encoding, expressions, warn
and na.action.  There are plenty of functions in R that violate other
principles of functional programming, so, by itself, this argument
seems a little weak to me.  There are obviously differences of opinion
about this issue in R core, and it's unfortunate that the user has to
be exposed to them through inconsistent function definitions.

Hadley

-- 
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