On Fri, 7 Jan 2011, Duncan Murdoch wrote:
On 11-01-07 12:08 AM, David Winsemius wrote:
I just tried ?Constants at the console and was disappointed that the
so-named base help page would not come up.
> ?Constants
No documentation for 'Constants' in specified packages and libraries:
you could try '??Constants'
Seems like there should have been a match. I was looking for the month
abbreviations, failing to hit the right name 4 times and then failing
3 more times on variations of what I remembered to be the name of that
page and finally ended up typing:
I do see that page as the first hit if I follow the advice and type
??Constants, though there seems to be a problem with the OSX help system and
that particular page.
But I agree with you, and will add Constants to the index.
I am not so sure: Constants seems rather to be a \concept entry, and
those are (deliberately) not searched by help()/?. (There is also the
question of capitalization: help() looks for exact matches.)
For future reference: Every help page has:
- a name (in this case "Constants"), which is what is displayed at the top
of the help page. It also determines the order in which pages are collated
into the full manual, if you build one of those.
- a title (which is a one-line explanation of the page); here it is
"Built-in constants". That is shown in the results from ??Constants.
- a number of aliases, which are indexed. Those are the things which work
with a single ?. In this case they are "LETTERS", "letters", "month.abb",
"month.name", and "pi".
- a filename (which you'll never see), in this case it's
src/library/base/man/Constants.Rd. That's the file to edit to make this
change.
In most cases the name is repeated as an alias, but for some reason
(flexibility?) that's not a requirement, and is not always the case, as here.
If I were designing the system I would say the name is automatically an
alias, but perhaps there are cases where that would be undesirable.
That was the case a decade ago, and it was found to be undesirable for
various reasons (one was the restrictions on the value for \name,
which used to be more severe than they are now). Another was that
where there were multiple matches the user was only offered one, so a
badly chosen \name in a contributed package could mask completely an
\alias in the standard system.
I'll add it as an alias here. I've passed on a message about the problem on
that page, and it should eventually be fixed.
Duncan Murdoch
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Brian D. Ripley, rip...@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
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