If statement generates two outputs
On Tue, 24 Mar 2009, Wacek Kusnierczyk wrote:
thanks. so it seems to be intentionally parsable, though i wouldn't say that this gives a meaning to ':=' -- the operator has a syntactic category, but no semantics. the syntactic category does not imply any semantics, as in '<-' = function(a, b) NULL 1 <- a # NULL where '<-' is still parsed the original way (as a LEFT_ASSIGN, gram.y again), but has now a completely different semantics. it looks like a bug to me: ':=' is parsed on par with '<-' as a LEFT_ASSIGN, but apparently is not backed by any function. it's a zombie. (unless rvalues is used, that is.)
yes, it's a zombie. It used to assign to the R system environment rather than the global workspace (roughly what is the base namespace now).
-thomas
Thomas Lumley Assoc. Professor, Biostatistics
tlumley at u.washington.edu University of Washington, Seattle