Github user felixcheung commented on a diff in the pull request:
https://github.com/apache/spark/pull/11220#discussion_r55474213
--- Diff: R/pkg/R/DataFrame.R ---
@@ -303,8 +303,28 @@ setMethod("colnames",
#' @rdname columns
#' @name colnames<-
setMethod("colnames<-",
- signature(x = "DataFrame", value = "character"),
--- End diff --
I think in this case the base:: definition is implemented in such a way
that it *should* (or at least it attempts to) handle different parameter types:
```
> getMethod("colnames<-")
Method Definition (Class "derivedDefaultMethod"):
function (x, value)
{
if (is.data.frame(x)) {
names(x) <- value
}
else {
dn <- dimnames(x)
if (is.null(dn)) {
if (is.null(value))
return(x)
if ((nd <- length(dim(x))) < 2L)
stop("attempt to set 'colnames' on an object with less than
two dimensions")
dn <- vector("list", nd)
}
if (length(dn) < 2L)
stop("attempt to set 'colnames' on an object with less than two
dimensions")
if (is.null(value))
dn[2L] <- list(NULL)
else dn[[2L]] <- value
dimnames(x) <- dn
}
x
}
<bytecode: 0x34c9058>
<environment: namespace:base>
Signatures:
x value
target "ANY" "ANY"
defined "ANY" "ANY"
```
So from what I can see the error you see actually comes from the base
implement, as "sort of" expected. Though I'm ok if we are to add explicit
checks to make the error more clear for the user.
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