DESCRIPTION: Imports: assertion of version?

Hi,

from 'Writing R Extensions' [R version 2.11.0 Under development
(unstable) (2010-03-16 r51290)] one can read:

"The optional `Imports' field lists packages whose name spaces are
imported from but which do not need to be attached. [...] Versions can
be specified, but will not be checked when the namespace is loaded."

Is it a design decision that version specifications are not asserted
for packages under "Imports:", or is it a "lack of implementation"?
If a design decision, under what use cases do you want to specify the
version but not validating it?  Is it simply because there is no
mechanism for tracking the origin/package of the code importing the
other package, and hence we cannot know which DESCRIPTION file to
check against?

On 3/19/10 6:13 AM, Henrik Bengtsson wrote:

Hi,

from 'Writing R Extensions' [R version 2.11.0 Under development
(unstable) (2010-03-16 r51290)] one can read:

"The optional `Imports' field lists packages whose name spaces are
imported from but which do not need to be attached. [...] Versions can
be specified, but will not be checked when the namespace is loaded."

Is it a design decision that version specifications are not asserted
for packages under "Imports:", or is it a "lack of implementation"?
If a design decision, under what use cases do you want to specify the
version but not validating it?  Is it simply because there is no
mechanism for tracking the origin/package of the code importing the
other package, and hence we cannot know which DESCRIPTION file to
check against?

I'm not aware of any use case in which the current lack of checking is a
"feature".  I would be interested in a patch (with testing) for this.

+ seth