(I'm not sure if this is a request for a feature, or another instance
where a feature has eluded me for many years.)
Often I have a function which calls other functions, and may often use
the default arguments to those functions, but needs the capability to
pass along non-default choices. I usually do this with some variation on
foo <- function(x, foo2Args=NULL or a list(foo2defaults),
foo3Args=NULL or a list(foo3defaults))
and then have logic to check for NULL, or use the list in combination
with do.call. It is also possible to do this with ..., but it always
seems a bit dangerous passing all the unnamed arguments along to all the
functions being called, especially when I always seem to be calling
functions that have similar arguments (maxit, eps, start, frequency, etc).
It is a situation I have learned to live with, but one of my
co-maintainers just pointed out to me that there should be a good way to
do this in R. Perhaps there is something else I have missed all these
years? Is there a way to do this cleanly? It would be nice to have
something like
foo <- function(x, foo2Args=as.missing(), foo3Args=as.missing())
then the call to foo2 and foo3 could specify foo2Args and foo3Args, but
these would get treated as if they were missing, unless they are given
other values.
Paul Gilbert
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