Behavior of saveRDS() and readRDS() in regard to objects' attributes

Yes, they do:

test <- structure(1:10, names=LETTERS[1:10], color='red', xxx='yyy')attr(test, which='uuu') <- 'zzz'test##  A  B  C  D  E  F  G  H  I  J ##  1  2  3  4  5  6  7  8  9 10 ## attr(,"color")## [1] "red"## attr(,"xxx")## [1] "yyy"## attr(,"uuu")## [1] "zzz"saveRDS(test, '/tmp/test.rds')test2 <- readRDS('/tmp/test.rds')identical(test, test2)## [1] TRUE

R relies heavily on these functions (as well as their variants). For example, they are used to save the user's workspace. Thus, it would be odd if they hadn't stored the attributes.

However, do note that you cannot store some "dynamically created" objects with these. This includes file and SQL db connections handlers, temporary SQL result handlers, etc. An example with RCpp compiled functions:

library('Rcpp')library('inline')   cppFunction("int one() { return 1; }")one() # it works## [1] 1one # contains a pointer to dynamically allocated mem chunk## function () ## .Primitive(".Call")(<pointer: 0x7f52c33a7680>)saveRDS(one, '/tmp/one.rds')

Now we restart R...

one <- readRDS('/tmp/one.rds')one # the pointer is no longer valid## function () ## .Primitive(".Call")(<pointer: (nil)>)one() # doesn't work## Error in .Primitive(".Call")(<pointer: (nil)>) : ##  NULL value passed as symbol address