[Rd] Increase transparency: suggestion on how to avoid namespaces and/or unnecessary overwrites of existing functions

Simon Urbanek simon.urbanek at r-project.org
Sun Oct 2 04:20:42 CEST 2011

On Oct 1, 2011, at 7:52 PM, Joshua Wiley wrote:

> On Sat, Oct 1, 2011 at 3:14 PM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
>> On 11-10-01 5:14 PM, Dominick Samperi wrote:
> [snip]
>>> Except that namespace::foo should be assigned to another local
>>> variable instead of using package::foo in a tight loop, because
>>> repeated calls to "::" can introduce a significant performance
>>> penalty. (This has been discussed in another thread.)
>> That's good advice too.
>> Duncan Murdoch
> Is this performance hit the sort of thing that byte compiling would help with, or am I misunderstanding its use?

Depending on what you mean ;). If you mean that compiling code containing :: removes the issue, yes, that is indeed true (i.e., foo::bar gets compiled into the actual value since the compiler can assume that it is a constant and thus :: is not actually called).

If you mean that compiling base and thus :: then that helps only to a degree. According to microbenchmark the overhead of :: is in the order of 7.5ms when compiled and 11ms when not compiled on my test machine (Xeon X5690 and R-devel which is actually much faster than the 30ms in R 2.13.1). If the time spent in your actual function is in the order of  microseconds then the overhead is still huge in either case. If it's much bigger then either doesn't matter.


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