[Rd] Package dependencies and imports

[Martin Maechler]

>>>>> "JohnF" == John Fox <jfox at mcmaster.ca>
>>>>>     on Thu, 21 Sep 2006 11:22:17 -0400 writes:

    JohnF> Dear list members,

    JohnF> I'm encountering the following problem with package dependencies and
    JohnF> imports: 

    JohnF> The Rcmdr package doesn't declare a formal dependency
    JohnF> (via depends or suggests in the package DESCRIPTION)
    JohnF> on the rgl package because the latter apparently
    JohnF> causes problems on some systems. This allows the
    JohnF> Rcmdr package to build and check on systems without
    JohnF> rgl present; if rgl isn't present, then menu items
    JohnF> using it are disabled (in the development version of
    JohnF> the Rcmdr package, not installed in the first place).

    JohnF> If rgl is present, however, the Rcmdr package uses
    JohnF> some unexported functions in it. I've done this via
    JohnF> rgl::: to avoid importing from the rgl namespace:
    JohnF> Because rgl isn't declared as a dependency, I can't
    JohnF> import its namespace. In the current R 2.4.0 alpha
    JohnF> and R 2.5.0 devel, however, using rgl::: generates a
    JohnF> warning when the package is checked.

    JohnF> Is there a way around this short of literally copying the unexported
    JohnF> functions in rgl that Rcmdr uses?

I think you should use the new DESCRIPTION field and say
  'Enhances: rgl'

but I haven't checked if this prevents the warning,  though I
think it should..

Regards,
Martin