[Rd] names function for environments?

[Martin Maechler]

>>>>> Michael Lawrence <lawrence.michael at gene.com>
>>>>>     on Tue, 27 Jan 2015 07:59:59 -0800 writes:

    > Since the contract of ls() is to sort, there is nothing wrong with
    > programmers depending on it. And there are many functions that could be
    > made 60X faster, but is it worth it? But I did notice that
    > as.list.environment has a sorted=FALSE argument already, so I guess
    > identical(names(x), names(as.list(x))) could be made to be TRUE, assuming
    > the order is at least persistent, if undefined, so that is a nice property.
    > I guess I'm OK it with.

As we ended only hearing "pro"s and no real "con"s,
I've committed (a corrected version of) the code now.

The above identity is not true in generality though,  but

	identical(names(x), names(as.list(x, all.names=TRUE)))

is now for an environment 'x'.

One could think to change the default of 'all.names' in 
as.list.environment(.) from FALSE to TRUE,
but that may break code in subtle places and I don't think we
should go there.

Martin


    > On Tue, Jan 27, 2015 at 7:44 AM, Peter Haverty <haverty.peter at gene.com>
    > wrote:

    >> I think that the "sorted" and "all.names" arguments are really only
    >> appropriate for pretty printing to the screen. I think it is a bit
    >> unfortunate that environments have a names accessor that is 60X slower
    >> than all the other types. This is likely due to the history of
    >> environments, which were originally just for behind-the-scenes tasks.
    >> 
    >> Now that users can use environments as hashes, we really need
    >> something like a "keys" function. We don't want programmers depending
    >> on the sorted-ness, as Martin mentioned.  Also, I think it helps users
    >> when objects share as many of the key API functions as possible.
    >> "names" is natural. "ls" was certainly confusing for me when I
    >> started. Having to supply two additional arguments to get the desired
    >> output doesn't help there.  Think of all the perl programmers
    >> struggling to switch to R.  Let's help them out.
    >> Pete
    >> 
    >> ____________________
    >> Peter M. Haverty, Ph.D.
    >> Genentech, Inc.
    >> phaverty at gene.com
    >> 
    >> 
    >> On Tue, Jan 27, 2015 at 7:26 AM, Michael Lawrence
    >> <lawrence.michael at gene.com> wrote:
    >> > I think ls(, sort=FALSE) would be more explicit and thus clearer. There
    >> is
    >> > much precedent for having arguments that request less work to be done
    >> e.g.
    >> > unlist(use.names=FALSE).  Yes, the extra typing is a bit painful, but
    >> there
    >> > is no intuitive reason why names() would be unsorted, while ls() would be
    >> > sorted. While it is tempting to use an existing function for this, the
    >> word
    >> > "names" is somewhat loaded. For example, one might expect
    >> > identical(names(env), names(as.list(env))) to be TRUE. I see no problem
    >> with
    >> > making names() a simple alias of ls(), as long as the behavior is the
    >> same.
    >> > Maybe a different name would be less "loaded" and imply lack of order,
    >> > something like keySet(). But do we really need this?
    >> >
    >> >
    >> >
    >> >
    >> >
    >> >
    >> > On Tue, Jan 27, 2015 at 7:11 AM, Martin Maechler
    >> > <maechler at lynne.stat.math.ethz.ch> wrote:
    >> >>
    >> >> >>>>> Peter Haverty <haverty.peter at gene.com>
    >> >> >>>>>     on Sun, 25 Jan 2015 12:21:04 -0800 writes:
    >> >>
    >> >>     > Hi all,
    >> >>     > The "ls" function wears two hats. It allows users to inspect an
    >> >>     > environment interactively and also serves deeper in code as the
    >> >>     > accessor for an environment's names/keys. I propose that we
    >> separate
    >> >>     > these two conflicting goals, keeping ls for interactive use and
    >> >> adding
    >> >>     > names for a quick listing of the hash keys. This involves adding
    >> two
    >> >>     > lines to do_names in attrib.c.
    >> >>
    >> >>     > The 'ls' function and its 'objects' synonym appear very frequently
    >> >> in
    >> >>     > performance-critical code like base/R/namespace.R and throughout
    >> the
    >> >>     > methods package. These functions are currently among the major
    >> >>     > contributors to execution time in package loading.
    >> >>
    >> >>     > This two-line addition to attrib.c gives a significant speedup for
    >> >>     > listing an environment's names/keys (2-60X depending on the
    >> 'sorted'
    >> >>     > argument). It also simplifies the environment API by making it
    >> more
    >> >>     > like the other basic types. We already have $ and [[ after all.
    >> >>
    >> >>     > Rather than sprinkling sorted=FALSE throughout the methods and
    >> base
    >> >>     > code, let's use names.
    >> >>
    >> >> as for list()s and other (generalized) vectors.
    >> >>
    >> >> This sounds appealing at first, and I have heard/seen others propose
    >> >> it.  I see one good reason *not* to allow it (and you mention the
    >> >> reason by mentioning 'sorted') :
    >> >>
    >> >> The contents of an environment are inherently unordered, and
    >> >> even if the order stays fixed for a while, no code should rely
    >> >> on the ordering of the objects, and for that reason,
    >> >>  <env>[1]  etc do not make sense and are not allowed.
    >> >>
    >> >>     > Would you be open to this change?
    >> >>
    >> >> I'm undecided currently:
    >> >>  "-": reason above;
    >> >>  "+": convenience, compacter R code using it;
    >> >>       very simple and natural change to src/main/attrib.c
    >> >>
    >> >> and waiting for other comments, not the least from other members of R
    >> core
    >> >> ..
    >> >>
    >> >> Martin Maechler, ETH Zurich
    >> >>
    >> >>
    >> >>     > I have submitted a patch and some timings to the bug tracker as
    >> >>     > https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=16170
    >> >>
    >> >>     > Regards,
    >> >>     > Pete
    >> >>
    >> >>     > ____________________
    >> >>     > Peter M. Haverty, Ph.D.
    >> >>     > Genentech, Inc.
    >> >>     > phaverty at gene.com
    >> >>
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    >> >>
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