Re: [Caml-list] Dependencies between plugins

["François Bobot" <francois.bobot@cea.fr>]

On 27/04/2015 12:16, Gabriel Scherer wrote:
> Another (more general, less ad-hoc) way to have this semantics would be to introduce a "default
> value" for predicates that do not explictly appear in rules. Under the set of default values D, then
> a rule depending on predicates P would be true if the boolean assignment (D,P=true) holds, with the
> rightmost boolean assignment shadowing all others. I mean that the rule
>
>    foo(x1,x2,x3) = ...
>
> would be applied whenever x1=true, x2=true, x3=true with an empty default environment, but with the
> default (y1=true, x1=false, y2=false) it would only be applied whenever (y1=true, x1=true, y2=false,
> x2=true, x3=true).
>
> Then setting "plugin=false" in the default environment (equivalently, -plugin) would give the
> expected semantics, I believe. In particular (thanks to François for his clear re-explanation on
> April 9) then the rule archive(native) would not be matched by the query archive(native,plugin).
>

I'm not sure it is usable because "archive" is not the only variable we use. For example "requires" 
is also a variable. So in an environment with `plugin=false`, `requires = "foo"` is not taken into 
account when looking for the dependencies with predicate `native=true,plugin=true`.

Perhaps your idea can be refined by making the default environment linked to specific variables. 
`plugin=false` is used only for `archive`.

-- 
François