Hi,
I am puzzled with serialize(). It comes down generating identical
hash codes for (apparently) identical objects using digest::digest(),
which in turn relies on serialize(). Here is an example illustration
the issue:
ser <- function(object, ...) {
list(
names = names(object),
namesRaw = charToRaw(names(object)),
ser = serialize(names(object), connection=NULL, ascii=FALSE)
)
} # ser()
# Object to be serialized
key <- key0 <- list(abc="Hello");
# Store results
d <- list();
# 1. As is
d[[1]] <- ser(key);
# 2. Set names and redo (hardwired: identical to what's already there)
names(key) <- "abc";
d[[2]] <- ser(key);
# 3. Set names and redo (generic: char->raw->char)
key <- key0;
names(key) <- sapply(names(key), FUN=function(name) rawToChar(charToRaw(name)));
d[[3]] <- ser(key);
# All names are identical
for (kk in 2:length(d))
stopifnot(identical(d[[1]]$names, d[[kk]]$names));
# All raw names are identical
for (kk in 2:length(d))
stopifnot(identical(d[[1]]$namesRaw, d[[kk]]$namesRaw));
# But, the serialized names differ.
print(identical(d[[1]]$ser, d[[2]]$ser));
print(identical(d[[1]]$ser, d[[3]]$ser));
print(identical(d[[2]]$ser, d[[3]]$ser));
So, it seems like there is some extra information in the names
attribute that is part of the serialization. Is it possible to show
they differ at the R level? What is that extra information?
Promises...?
Please enlighten me.
Henrik
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