[R] Assigning default function arguments to themselves: Why?

[andrewH]

Dear Bill--

I have seen it most often in functions that are defined or used inside of
other functions, and need an argument from the calling function.  So I have,
purely as a matter of imitation, taken to doing it when I am writing a
function that wants an argument of the calling function passed to it
unchanged, because that is how I saw it used. So for instance, in
read.table(), scan() is called several times with reflexive argument
assignments that include:
file = file
what = what
sep = sep
quote = quote
comment.char = comment.char
allowEscapes = allowEscapes
encoding = encoding

Is this what you mean by an example that 'works'? I am sort of foggy on the
shade of meaning conveyed by the single quotes. If not, let me know what
kind of example you want, and I'll try and find it.



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