[Rd] On implementing zero-overhead code reuse

[frederik at ofb.net]

Hi Kynn,

Thanks for expanding.

I wrote a function like yours when I first started using R. It's
basically the same up to your "new.env()" line, I don't do anything
with environmentns. I just called my function "mysource" and it's
essentially a "source with path". That allows me to find code I reuse
in standard locations.

I don't know why R does not have built-in support for such a thing.
You can get it in C compilers with CPATH, and as you say in Perl with
PERL5LIB, in Python, etc. Obviously when I use my "mysource" I have to
remember that my code is now not portable without copying over some
files from other locations in my home directory. However, as a
beginner I find this tool to be indispensable, as R lacks several
functions which I use regularly, and I'm not necessarily ready to
confront the challenges associated with creating a package.

However, I guess since we can get your functionality pretty easily
using some lines in .Rprofile, that makes it seem less important to
have it built-in. In fact, if everyone has to implement their own
version of your "import", this almost guarantees that the function
won't appear by accident in any public code. My choice of name
"mysource" was meant to serve as a more visible lexical reminder that
the function is not meant to be seen by the public.

By the way, why do you do the stuff with environments in your "import"
function?

Dirk's take is interesting. I don't use version control for my
personal projects, just backing-up. Obviously not all R users are
interested in becoming package maintainers, in fact I think it would
clutter things a bit if this were the case. Or maybe it would be good
to have everyone publish their personal utility functions, who knows?
Anyway I appreciate Dirk's arguments, but I'm also a bit surprised
that Kynn and I seem to be the only ones who have written personal
functions to do what Kynn calls "zero-overhead code reuse". FWIW.

Cheers,

Frederick

On Sun, Oct 02, 2016 at 08:01:58PM -0400, Kynn Jones wrote:
> Hi Frederick,
> 
> I described what I meant in the post I sent to R-help
> (https://stat.ethz.ch/pipermail/r-help/2016-September/442174.html),
> but in brief, by "zero overhead" I mean that the only thing needed for
> library code to be accessible to client code is for it to be located
> in a designated directory.  No additional meta-files, packaging/compiling,
> etc. are required.
> 
> Best,
> 
> G.
> 
> On Sun, Oct 2, 2016 at 7:09 PM,  <frederik at ofb.net> wrote:
> > Hi Kynn,
> >
> > Do you mind defining the term "zero-overhead model of code reuse"?
> >
> > I think I understand what you're getting at, but not sure.
> >
> > Thank you,
> >
> > Frederick
> >
> > On Sun, Oct 02, 2016 at 01:29:52PM -0400, Kynn Jones wrote:
> >> I'm looking for a way to approximate the "zero-overhead" model of code
> >> reuse available in languages like Python, Perl, etc.
> >>
> >> I've described this idea in more detail, and the motivation for this
> >> question in an earlier post to R-help
> >> (https://stat.ethz.ch/pipermail/r-help/2016-September/442174.html).
> >>
> >> (One of the responses I got advised that I post my question here instead.)
> >>
> >> The best I have so far is to configure my PROJ_R_LIB environment
> >> variable to point to the directory with my shared code, and put a
> >> function like the following in my .Rprofile file:
> >>
> >>     import <- function(name){
> >>         ## usage:
> >>         ## import("foo")
> >>         ## foo$bar()
> >>         path <- file.path(Sys.getenv("PROJ_R_LIB"),paste0(name,".R"))
> >>         if(!file.exists(path)) stop('file "',path,'" does not exist')
> >>         mod <- new.env()
> >>         source(path,local=mod)
> >>         list2env(setNames(list(mod),list(name)),envir=parent.frame())
> >>         invisible()
> >>     }
> >>
> >> (NB: the idea above is an elaboration of the one I showed in my first post.)
> >>
> >> But this is very much of an R noob's solution.  I figure there may
> >> already be more solid ways to achieve "zero-overhead" code reuse.
> >>
> >> I would appreciate any suggestions/critiques/pointers/comments.
> >>
> >> TIA!
> >>
> >> kj
> >>
> >> ______________________________________________
> >> R-devel at r-project.org mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-devel
> >>
> 

On Sun, Oct 02, 2016 at 08:05:53PM -0400, Kynn Jones wrote:
> On Sun, Oct 2, 2016 at 8:01 PM, Kynn Jones <kynnjo at gmail.com> wrote:
> > Hi Frederick,
> >
> > I described what I meant in the post I sent to R-help
> > (https://stat.ethz.ch/pipermail/r-help/2016-September/442174.html),
> > but in brief, by "zero overhead" I mean that the only thing needed for
> > library code to be accessible to client code is for it to be located
> > in designed directory.  No additional meta-files, packaging/compiling,
>      ^^^^^^^^
> 
> Sorry, I meant to write "designated".
> 
> > etc. are required.
> 

On Sun, Oct 02, 2016 at 07:18:41PM -0500, Dirk Eddelbuettel wrote:
> 
> Kynn,
> 
> How much homework have you done researching any other "alternatives" to the
> package system?  I know of at least one...
> 
> In short, just about everybody here believes in packages. And repositories.
> And package management.  And version control (at the package level). And
> maybe byte compilation.  And associated documentation.  And unit tests.  And
> continuous integration.
> 
> You don't have to -- that's cool.  Different strokes for different folks.
> 
> But if think you need something different you may just have to build that
> yourself.
> 
> Cheers, Dirk
> 
> -- 
> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
>