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
tlum...@u.washington.edu University of Washington, Seattle
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