On 2009-07-21, at 01:18 , Robert Goldman wrote: > james anderson wrote: >> On 2009-07-21, at 00:35 , Robert Goldman wrote: [...] >> >>> What would it mean, for >>> example, to be :contingent-on or :weakly-depend on a :file? >> >> if the file is present, then the contingent component is included in >> the system and dependent on that file. >> no different than a simple dependency. the only difference are in the >> effective behaviour of operate. >> in my case it makes it possible to do things like include a ffi >> interface iff dependent on runtime conditionalization and include a >> particular aspect of the higher level interface iff the particular >> ffi interface is there. > > I don't believe that is correct.
? in that weakly-depends-on does not do this, or this is not a "correct" thing to do? i do not use weakly-depends-on. i implemented :contingent-on. > If you look at the source, > weakly-depends-on is not handled as a first class citizen, the way > :depends-on is. :depends-on is squirreled away in a slot, and then > manipulated at the time we carry out an ASDF operation. The WEAKLY > part > of :weakly-depends-on, on the other hand (1) only works when the > dependency is on a system, not a feature or a file and (2) is resolved > when the defsystem is "parsed". I.e., there's no way you can load a > system that has weakly-depends on, THEN define another system on which > it weakly depends, and have the first system do anything reasonable. > The :weakly-depends-on is gone by the time the second system is > introduced to your lisp image. weakly depends on may well not be well implemented. i do not use it. >> >>> Unfortunately, :weakly-depend-on can be parsed off an arbitrary >>> component, not just a system. Oh. Looking at the source, I see >>> that >>> weakly-depends on only works on a system name. This means that >>> >>> (defsystem foobar >>> :weakly-depends-on ((feature "foo")) >>> >>> is not permitted, which seems wrong. That is, it seems wrong until >>> you >>> realize that the feature would be interpreted at the time the >>> defsystem >>> form is READ, not at the time you try to operate on the system. >>> >>> The more I think about this, the more queasy it makes me feel... >> >> it's an argument to re-implement it correctly - that is with a >> uniform semantics > > Yes, I agree. This should be redone properly. > > In the meantime, I am inclined to think I should rewrite my > weakly-depends-on documentation to explain the irregularities that are > hidden there. > > > Best, > r _______________________________________________ asdf-devel mailing list asdf-devel@common-lisp.net http://common-lisp.net/cgi-bin/mailman/listinfo/asdf-devel
