Dave Cooper wrote: > > Hi, > > Is stuff like the following advised/recommended? > > ;;;;; > (asdf:defsystem #:robot > :description "The Gendl™ Simplified Android Robot example " > ... > :depends-on (#-gendl :gendl) > ... ) > ;;;;;; > > > The scenario is that we ship a pre-built Gendl image which has no asdf > or Quicklisp in it (but does, of course, have :gendl included in > *features). > > Downstream user is then free to load Quicklisp and start pulling in > libraries. But if they pull a library (or application, like :robot), > which normally should depend-on :gendl, then we don't want it trying to > reload the whole gendl system, since it's already built in. > > I know this was discussed here briefly around the launch of 3.0.3 but > I'm still not completely clear on how it should work. If we don't > include ASDF and Quicklisp at all in our pre-built image, then I don't > see any way for us to tamper with e.g. asdf's registry search functions. > I guess the only way to do that would be to provide a custom function > for installing Quicklisp and ASDF -- but we have no guarantee that the > user will actually follow our function and not simply try to install > Quicklisp according to the instructions at quicklisp.org > <http://quicklisp.org>.
I think it's fair to say that there are differences of opinion about this. One school of thought would deprecate these, favoring a declarative syntax for ASDF:DEFSYSTEM. They wouldn't like such use of reader macros because it "hides" information from ASDF. I am of a more pragmatic school that thinks these are fine. While I like declarative systems when possible, I'm not convinced that they are always realizable. I have a case very similar to yours where I have done exactly the same thing and put a #-<system> <system> in :depends-on, because ASDF does not correctly detect that <system> need not be reloaded in the prebuilt image we have. It's particularly an issue for us since the system in question *cannot* be loaded twice: if you attempt to do so, it compromises the state of the lisp image so that it is no longer usable. cheers, r
