RFC: What should ?foo do?

On Fri, 25 Apr 2008, Deepayan Sarkar wrote:

For what it's worth, I use ?foo mostly to look up usage of functions
that I know I want to use, and find it perfect for that (one benefit
over help() is that completion works for ?). The only thing I miss is
the ability to do the equivalent of help("foo", package = "bar");
?bar::foo gives the help page for "::". Perhaps that would be
something to consider for addition.

That fits most naturally with the (somewhat technical) idea that bar::foo 
becomes a symbol and not a function call.  I believe that several of think 
that is in principle a better idea, but no one has as yet (AFAIK) explored 
the ramifications.

However, 5 mins looking at the sources suggests that it is easy to do.

And you already did.  Thanks!

I'm going to make the following change soon (in R-devel).

??foo

will now be like help.search("foo").  This will work with your change, 
so ??utils::foo will limit the search to the utils package.  This is 
also quite easy.  A more difficult thing I'd like to do is to broaden 
the search to look outside the man pages, but that's a lot harder, and I 
haven't started on it.

I will also follow Hadley's suggestion and change the format of the 
help.search results, so you can just cut and paste after a question mark 
to look up the particular topic, e.g.  ??foo gives

utils::citEntry         Writing Package CITATION Files

Type '?PKG::FOO' to inspect entry 'PKG::FOO TITLE'.

I haven't touched the case of ?foo failing; I'll want to try it for a 
while to decide whether I like it best as is:

 > ?foo
No documentation for 'foo' in specified packages and libraries:
you could try '??foo'

or whether it should just automatically call help.search, or something 
in between.

Duncan Murdoch