>>>>> Dipterix Wang >>>>> on Fri, 11 Feb 2022 06:55:44 -0500 writes:
> Hi, > str2lang("") raises an error in current version. on purpose. > Would it > be good if it returns a missing value expression? Well, others may be able to better explain why "the empty name" aka your "missing value expression" or just "the missing" is a "dangerous" object and ideally it would not be available at all on the R level. OTOH, it is available e.g. via alist(), maybe slightly "less ugly" as alist(.=)$. but I don't think there are really good use cases. (see below) > One use-case would be to build an expression that subsets an > array: > # Expected: x[index1, ] > as.call(list(quote(`[`), quote(x), quote(index1), str2lang(""))) > Right now I'm using the following, which is ugly > as.call(list(quote(`[`), quote(x), quote(index1), alist(x=)[[1]])) Well, in such cases, much less ugly than both your version is to use substitute(), here e.g., > substitute(x[I,], list(I = quote(index1))) x[index1, ] > > Thanks, - Dipterix You are welcome, Martin {Please, for next time do use text/plain e-mail : } > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel