[Rd] Resolving functions using R's namespace mechanism can double runtime

[Seth Falcon]

On 4/27/10 1:16 PM, Dominick Samperi wrote:
> It appears that the runtime for an R script can more than double if a few
> references to a function foo() are replaced by more explict references
> of the form pkgname::foo().
>
> The more explicit references are of course required when two
> loaded packages define the same function.
>
> I can understand why use of this mechanism is not free in an
> interpreted environment like R, but the cost seems rather high.

`::` is a function, so there is going to be overhead.  OTOH, there is no 
reason to pay for the lookup more than once.  For example at startup, 
you could do:

myfoo <- pkgname::foo

And then later call myfoo() and I don't think you will see the added cost.

You can formalize the above approach in package code by renaming 
function in the importFrom directive where I believe you can do:

importFrom(pkgname, myfoo=foo)


+ seth

-- 
Seth Falcon | @sfalcon | http://userprimary.net/