Question about substitute() and function def

Duncan Murdoch <murdoch at stats.uwo.ca> writes:

 > substitute(function(a=a) 1, list(a=quote(foo)))

function(a = a) 1

   a bug for sure

Yes.

Hmm... The issue is that the argument to `function` is a pairlist (not
LANGSXP), and we don't recurse into those. Any R object can turn up as
part of objects of mode "call" (by various methods, not least call()
constructions), and I don't think we want to substitute into any
recursive object. However, it's unlikely that pairlists would be used
for anything other than function arguments, so I suppose we could
change the behaviour (special-casing calls to `function` is an
alternative). Luke?

To wit:

mode(quote(function(x)1)[[1]])

[1] "name"

mode(quote(function(x)1)[[2]])

[1] "pairlist"

mode(quote(function(x)1)[[3]])

[1] "numeric"

O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
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