More user-friendly error message needed.
On Wed, 07 Apr 2004 15:38:54 -0400, Duncan Murdoch <dmurdoch@pair.com> wrote :
There are several places this could be fixed. When you use x$z, the code for $ could give an error message or a warning; instead it returns NULL with no error or warning. Changing this would probably be dangerous: I'd guess there's code out there that relies on getting a NULL back from a construction like that. But maybe we should change that in 2.0?
No, this would be a bad idea. A standard test for the existence of a list element is if (is.null(x$z)) .... Those would all need some other kind of test if this were changed. Not a good idea at all! Duncan Murdoch