OK. I now have a version which seems to do the trick and reuses an
existing error message. Will commit to r-devel if and when make
check-devel succeeds.
-p
Peter Dalgaard wrote:
s...@userprimary.net wrote:
Thanks, Seth. Martin Morgan sent a patch for a few lines above yours,
which I didn't have a chance to review until now:
- if (!isVectorList(x) && LENGTH(y) > 1)
- error(_("more elements supplied than there are to replace"));
+ if (!isVectorList(x) && LENGTH(y) != 1)
+ if (LENGTH(y) == 0)
+ error(_("fewer elements supplied than there are to replace"));
+ else
+ error(_("more elements supplied than there are to replace"));
I _think_ that you are both right that there is no way for a zero-length
RHS not to be an error. E.g.,
> x[[0]] <- real(0)
Error in x[[0]] <- real(0) : attempt to select less than one element
The difference between Seth's solution and Martin's is whether to
pre-check for nsubs==1, and I don't think we want that because of
> x <- matrix(1:4,2,2)
> x[[2,2]]
[1] 4
> x[[2,2]] <- integer(0)
> x
[,1] [,2]
[1,] 1 3
[2,] 2 142000760
On 2/20/10 7:50 AM, Peter Dalgaard wrote:
You don't want to understand, believe me! ;-)
It's a bug, probably not the very worst kind, but accessing memory that
isn't yours is potentially harmful (but writing to it is considerably
worse).
Looks like the issue only concerns the right hand side; nothing to do
with the auto-expansion of v. I also get
v <- integer(0)
u <- integer(1)
u[[2]] <-v
u
[1] 0 142000760
u[[1]] <-v
u
[1] 142000760 142000760
a <- 1
a[[1]] <-v
a
[1] 142000760
I'm thinking this should be an error. Similar to:
v = 1
v[[1]] = integer(3)
Error in v[[1]] = integer(3) :
more elements supplied than there are to replace
But instead not enough elements supplied. Perhaps:
v[[1]] = integer()
Error in v[[1]] = integer() : [[ ]] replacement has zero length
The code in do_subassign2_dflt currently does not check that the
replacement has length > 0 for the nsubs == 1 case. I think we want:
@@ -1529,6 +1532,8 @@ do_subassign2_dflt(SEXP call, SEXP op, SEXP args,
SEXP rho)
if (nsubs == 0 || CAR(subs) == R_MissingArg)
error(_("[[ ]] with missing subscript"));
if (nsubs == 1) {
+ if (length(y) == 0)
+ error(_("[[ ]] replacement has zero length"));
offset = OneIndex(x, thesub, length(x), 0, &newname,
recursed ? len-1 : -1, R_NilValue);
if (isVectorList(x) && isNull(y)) {
x = DeleteOneVectorListItem(x, offset);
+ seth
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c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
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