[Rd] :: and ::: as .Primitives?

[William Dunlap]

> if I want to use foo::bar many times, say
> in a loop, I would do
>
> foo_bar <- foo::bar
>
> and use foo_bar, or something along those lines.

The foreach package does that with a function from the compiler package,
so that foreach can work on old version of R:
  comp <- if (getRversion() < "2.13.0") {
    function(expr, ...) expr
  } else {
    compiler::compile
  }
This results in foreach having its own copy of compiler::compile, with
namespace "compiler", but copied from the version of package:compile
existing on the machine that built the binary of foreach.  If you later
install
an updated version of the compiler package, then foreach still uses the old
compiler::compile, which may not work with the private functions in
the new version of package:compiler.

Making :: faster would not fix this particular problem (making 'comp' a
function that contained the if(getRVersion...) code would), but things
like this could cause problems when more people put 'myFunc <-
otherPackage::Func'
in their packages.




Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Thu, Jan 22, 2015 at 11:44 AM, <luke-tierney at uiowa.edu> wrote:

> I'm not convinced that how to make :: faster is the right question. If
> you are finding foo::bar being called often enough to matter to your
> overall performance then to me the question is: why are you calling
> foo::bar more than once? Making :: a bit faster by making it a
> primitive will remove some overhead, but your are still left with a
> lot of work that shouldn't need to happen more than once.
>
> For default methods there ought to be a way to create those so the
> default method is computed at creation or load time and stored in an
> environment. For other cases if I want to use foo::bar many times, say
> in a loop, I would do
>
> foo_bar <- foo::bar
>
> and use foo_bar, or something along those lines.
>
> When :: and ::: were introduce they were intended primarily for
> reflection and debugging, so speed was not an issue. ::: is still
> really only reliably usable that way, and making it faster may just
> encourage bad practice. :: is different and there are good arguments
> for using it in code, but I'm not yet seeing good arguments for use in
> ways that would be performance-critical, but I'm happy to be convinced
> otherwise. If there is a need for a faster :: then going to a
> SPECIALSXP is fine; it would also be good to make the byte code
> compiler aware of it, and possibly to work on ways to improve the
> performance further e.g. through cacheing.
>
> Best,
>
> luke
>
>
> On Thu, 22 Jan 2015, Peter Haverty wrote:
>
>
>  Hi all,
>>
>> When S4 methods are defined on base function (say, "match"), the
>> function becomes a method with the body "base::match(x,y)". A call to
>> such a function often spends more time doing "::" than in the function
>> itself.  I always assumed that "::" was a very low-level thing, but it
>> turns out to be a plain old function defined in base/R/namespace.R.
>> What would you all think about making "::" and ":::" .Primitives?  I
>> have submitted some examples, timings, and a patch to the R bug
>> tracker (https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=16134).
>> I'd be very interested to hear your thoughts on the matter.
>>
>> Regards,
>> Pete
>>
>> ____________________
>> Peter M. Haverty, Ph.D.
>> Genentech, Inc.
>> phaverty at gene.com
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>>
> --
> Luke Tierney
> Ralph E. Wareham Professor of Mathematical Sciences
> University of Iowa                  Phone:             319-335-3386
> Department of Statistics and        Fax:               319-335-3017
>    Actuarial Science
> 241 Schaeffer Hall                  email:   luke-tierney at uiowa.edu
> Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu
>
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

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