[Bioc-devel] GenomicFiles reducer and iterate argument
On 06/15/2014 07:34 AM, Michael Lawrence wrote:
Hi guys, Was just checking out GenomicFiles and was a little surprised that the arguments to the REDUCER are different depending on iterate=TRUE vs. iterate=FALSE. In my often flawed opinion, iteration should not be a concern of the REDUCER. It should be oblivious to the iteration mode. In other words, when iterate=TRUE, it is a special case of having two objects to combine, instead of multiple.
My 'rationale' was that one would choose iterate=FALSE when one required all elements to perform the reduction. I thought of the list (rather than ...) as the general R data structure for representing N elements, with a special case (consistent with Reduce) made for the pairwise reduction of iterate=TRUE. Either way, the two cases (x, y vs. list(), x, y vs. ...) seem to require some explaining to the user. Is there a clear better choice? You're the second person to trip over this, so I guess there's a crack in the sidewalk... Martin
What would be convenient (but unnecessary) is to detect from the formal
arguments whether REDUCER is variadic or list-based. In other words, if
REDUCER is defined like function(...) { } it is called via do.call(),
otherwise it is passed the list.
Thoughts? Maybe I'm totally confused?
Michael
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