offset arg (was Re: [R] variable scope)

Peter Dalgaard BSA
03 Aug 2002 13:29:15 +0200 writes:

> On 3 Aug 2002, Peter Dalgaard BSA wrote:
> > Another example that has come back to haunt us several times is
> > lm(...,data=d,offset=foo). The problem is that we want "foo" to be
> > found inside "d" if present, but call-by-value semantics imply that it
> > is an object in the caller's scope. You really ought to pass the name
> > "foo" (or maybe better: quote(foo), or a formula ~foo).
> Should we not just deprecate the offset argument in lm and glm?  Using the
> offset() function in the formula works as one would expect (at least if
> one remembers the R rules which start at the formula's environment).

That's a definite possibility, but what about subset (the argument,
not the function) and weights? 

Not to mention pch and col in plot.formula et al. where vectorization
led to some unexpected awkwardness.

   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (             FAX: (+45) 35327907
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