> Both of these are possible in C. See: > > https://stat.ethz.ch/pipermail/r-devel/2007-September/046943.html
Cool, thanks. > It shows how to query an object to see if its a promise and but rather > than extract the environment it shows how to copy a promise without > evaluating it; however, it was also my experience that these two were > what was actually needed rather than being able to extract the > environment. > > I would also recommend you do some testing since I found that adding > promises did not always make as big a difference in performance as I > had hoped and the added complexity may not be worth it in all cases. > For example, I had a version of proto that supported promises but > ggplot2 only ran slightly faster with it so I did not pursue it any > further. On the other hand if you are doing it to support > self-referential structures then that is a different matter. I'm mainly interested in this for pedagogy - giving students some tools to inspect promises without evaluating them would be useful. Hadley -- RStudio / Rice University http://had.co.nz/ ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
