introspective capabilities

Duncan Murdoch <murdoch.duncan at gmail.com> writes:

On 27/08/2010 7:52 AM, Christophe Rhodes wrote:

Hi,

Is there any way, from R code, to perform introspection as to where
certain names acquired their values?

There's the "keep.source" option to source() and the optional
"srcfile" argument to parse() that tell R to keep this information.
If you haven't changed the default
getOption("keep.source") from TRUE, then source will default to
keeping it, and you can find the original location of a function
definition for function f by looking in attr(body(f), "srcref").  See
?srcref for the format; there aren't a lot of user-level utility
functions for working with this.

Thanks.  This is enough for my immediate purposes: supporting
single-keystroke (M-.) jumping to source locations of functions.

For packages, the relevant option is "keep.source.pkgs" at the time
the package is installed.

Thank you.

Is there anything like a cross-referencing database within R?  The
functionality I'm looking for here is to be able to name a function, and
come back with a list of functions (or srcrefs) where that name is
used.  (I realise that this is not in general possible; just the
lexically-apparent cases would be enough).