On 5/16/16 May 16 -4:36 PM, Faré wrote:
On Mon, May 16, 2016 at 3:35 PM, Robert Goldman <rpgoldman@sift.net> wrote:
Is it just me, or is the :FEATURE dependency-def form undocumented in the manual? It is *mentioned* in the grammar, but I don't see it documented -- except for the misleading mention that the :FEATURE *requirement* has been removed from ASDF.
There were two :FEATURE features. One was braindead and I removed it in ASDF3, because it was badly breaking the object model.
Right. I believe that's the one documented as "feature requirement." Some of this is a problem that arises because we don't have a DEFSYSTEM *Semantics* section, only a DEFSYSTEM *grammar*.
1. if the FEATURE is present, include dependency-def and 2a. If the FEATURE is absent FAIL or 2b. If the FEATURE is absent, quietly succeed.
2b. Basically it's a (:when-feature :foocl "foocl-support") Maybe it should have been named :when-feature, but I believe the name was also from ASDF1, except that that feature feature was badly broken and I had to fix it!
OK. I will try to add a subsection about the semantics to the defsystem grammar page (per my earlier remarks, not ideal, but I'm not ready to plunge into the end-to-end rewrite and reorg that the manual requires!).
If the semantics is intended to be the latter -- and that's how I read the relevant code in find-component.lisp -- how does a programmer say "if this feature is not present, my system should not compile"?
(:feature (:not :foocl) "something_that_fails")
Would it be possible for us to either add something that fails as (:feature (:not :foocl) :fail) or perhaps better (the above smells uncomfortably like :IF-COMPONENT-DEP-FAILS): (:required-feature <feature-expression>) "require" is, perhaps unfortunately, a term of art for CL so perhaps (:must-have-feature <feature-expression>) would be better.... One more query while I have you on the line: the grammar still contains this rule: component-dep-fail-option := :fail | :try-next | :ignore The LHS of that rule is never referenced, so I propose to cut it. Thanks for the advice & clarification, r