Hi Paul,
> `:::`
function (pkg, name)
{
pkg <- as.character(substitute(pkg))
name <- as.character(substitute(name))
get(name, envir = asNamespace(pkg), inherits = FALSE)
}
<environment: namespace:base>
and
> `::`
function (pkg, name)
{
pkg <- as.character(substitute(pkg))
name <- as.character(substitute(name))
ns <- tryCatch(asNamespace(pkg), hasNoNamespaceError = function(e) NULL)
if (is.null(ns)) {
pos <- match(paste("package", pkg, sep = ":"), search(),
0L)
if (pos == 0)
stop(gettextf("package %s has no name space and is not on
the search path"),
sQuote(pkg), domain = NA)
get(name, pos = pos, inherits = FALSE)
}
else getExportedValue(pkg, name)
}
<environment: namespace:base>
are the reasons I think.
Jeff
On Wed, Feb 16, 2011 at 12:13 PM, Paul Gilbert
<pgilb...@bank-banque-canada.ca> wrote:
> (subject changed from: RE: [Rd] Avoiding name clashes: opinion on best
> practice naming conventions)
>
> Dominick
>
> Is this really true? Is there a speed advantage to defining a local function
> this way, say, within another function, and then calling it within a loop
> rather than the original? Do you have data on this?
>
> Paul
>
>> -----Original Message-----
>> From: r-devel-boun...@r-project.org [mailto:r-devel-bounces@r-
>> project.org] On Behalf Of Dominick Samperi
>> Sent: February 16, 2011 12:44 PM
> ...
>> Since the resolution of myPkg::foo() occurs at runtime (via a function
>> call) instead
>> of at compile time (as it would in C++), this practice can introduce a
>> significant
>> performance hit. This can be avoided by doing something like:
>> mylocalfunc <- myPkg::foo
>> [tight loop that uses mylocalfunc repeatedly]
>>
>> Here mylocalfunc would not be exported, of course.
>>
>> Dominick
> ...
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--
Jeffrey Ryan
jeffrey.r...@lemnica.com
www.lemnica.com
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