[R] %+=% and eval.parent()
p.dalgaard at biostat.ku.dk
Fri Apr 9 14:41:24 CEST 2004
Prof Brian Ripley <ripley at stats.ox.ac.uk> writes:
> > This *should* be somewhere in the R Language Definition, although I'm
> > not sure it is actually there. Or the blue book, although I suspect
> > that S v.3 actually used positional matching (and jumped through
> > hoops).
> It did. This is in the FAQ, 3.2.3:
> * In R, the argument of a replacement function which corresponds to the
> right hand side must be named `value'. E.g., `f(a) <- b' is evaluated
> as `a <- "f<-"(a, value = b)'. S always takes the last argument,
> irrespective of its name.
> I seem to recall I discovered the discrepancy in ca 1998.
I seem to recall when we introduced it, and that it was deliberate.
What I can't remember is what the occasion was.
> R-lang is minimalist about what it calls `assignment functions', most of
> the time.
`replacement functions' would be correct terminology, right? <- and
<<- are the assignment functions.
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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