There is an unannounced and non-backwards-compatible change to the behaviour of
'get' in R2.8.0. 'get'ting a missing value now causes an error, whereas
hitherto it's just returned a "missing" object. For example, in R2.8.0 this
happens:
test> getto <- function( x) get( 'x', sys.frame(1))
test> getto()
Error in get("x", sys.frame(1)) :
argument "x" is missing, with no default
whereas in R2.7.1 this happens:
test> getto()
test>
i.e. a "missing" object.
While I can see some reason to the change, the error always would have gotten
triggered eventually if it actually mattered-- and the new behaviour is
inconsistent with other extraction functions:
test> getto2 <- function(x) sys.frame(1)$x
test> getto2()
test>
and the same goes for '[['.
'mget' also returns a missing object, rather than tripping an error.
The new 'get' breaks code in packages 'mvbutils' and 'debug'. At least 54
separate functions in those packages use 'get', so there'd be a fair bit of
work in checking & changing all these to 'mget'! (Not to mention the entire
rest of my code body...)
Is it possible to 'get' the old behaviour back?
Mark Bravington
CSIRO Mathematics & Information Science
CSIRO Marine Lab
Hobart
Australia
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
