On Wed, 1 Jun 2011, Thomas Friedrichsmeier wrote:
Hi,
On Tuesday 31 May 2011, [email protected] wrote:
Yes you should. Changing things in other people's packages is not a
safe thing to do.
sorry to insist, but I was hoping for a slightly more specific pointer. I'll
try asking it another way:
Suppose I was using assignInNamespace() entirely bona fide, i.e. to develop and
test patches with the intent to offer them to the package maintainer(s) for
inclusion. What sort of gotchas should I be looking out for, specifically with
respect to the compiler? Also, if the package that I'm trying to improve is a
base package?
At the moment the main issue is that the assignment may not have any
effect on compiled code because the compiled code accesses the
finctionality known to be provided by these funcions in some more
direct way. Examples are BUILTIN functions, which are called directly
through the internal table, and some functions that are simple
wrappers around .Internal calls where the compiled code in effect goes
directly to the .Internal call. At the moment this applies only to
some functions in base packages but may in the future extend to other
packages.
Best,
luke
Regards
Thomas
P.S.: Just to let you know, why I do not feel too much ashamed or scared of
changing things in other people's packages, here's (slighlty simplified) the
pattern that I'm following:
backup <- original
replacement <- function() {
call.my.hook()
eval(body(backup))
}
formals(replacement) <- formals(backup)
environment(replacement) <- environment(backup)
assignInNamespace(...)
I know that leaves subtle differences beyond anything the compiler may be
doing, such as in the sys.calls(). I am also pretty certain that these subtle
differences are completely irrelevant *in those functions that I modify* this
way. And I have a bunch of automated tests to make me sleep better, too.
Ok, and for a select few functions, my replacements are more "radical", such
as for utils::savehistory(). But then, that is essentially non-functional in
my use-case in its original incarnation, in the first place, so I'm not really
scared of making things worse, there, either.
--
Luke Tierney
Statistics and Actuarial Science
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: [email protected]
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
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