[Rd] Re: [R] More user-friendly error message needed.

[Duncan Murdoch]

On Wed, 07 Apr 2004 15:38:54 -0400, Duncan Murdoch <dmurdoch at 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