[Rd] Changing function arguments to NULL
Prof Brian Ripley
ripley at stats.ox.ac.uk
Mon Feb 28 23:28:34 CET 2005
On Mon, 28 Feb 2005, McGehee, Robert wrote:
> But passing list(NULL) or NULL into a function may have entirely
> different results.
For a replacement operator expecting a list, list(NULL) *is* what you
want. BTW, this is FAQ 7.1.
> foo <- alist(x = 5, y = 2, z = 3)
> foo["x"] <- list(NULL)
if (as I guess) you want to set the default value to NULL, not `the
argument to NULL'.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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