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

[Thomas Lumley]

On 3 Aug 2002, Peter Dalgaard BSA wrote:

> ripley@stats.ox.ac.uk 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.

Though at least for the graphical parameters I think with() gives a good
solution.

	-thomas

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