Thanks for the clear discussion. Maybe best to just return NIL for type always then.
This has the potential added advantage that if it causes bugs, the bugs will /also/ appear on SBCL, which seems like the most tested configuration! Best, r On 3/15/10 Mar 15 -10:32 PM, Faré wrote: >>> Should we use :unspecific based on a whitelist of known-working >>> implementations, or should we just avoid it altogether? >> >> Either of those seems OK to me. I think a blacklist is probably wrong, >> just because it's too hard to update. >> > Agreed. > >> OTOH, I don't really understand the motivation in two places here: >> >> 1. I don't understand the rationale for the prohibition in the CLHS >> (probably someone from one of the implementation groups can say >> something about this) and >> > For backwards-compatibility probably, the CLHS allowed implementations > to NOT implement :unspecific. Some indeed don't (CLISP and ABCL at least). > >> 2. I don't know the rationale for returning it from SPLIT-NAME-TYPE. I >> understand that :unspecific has different behavior under merging (which >> is why I don't understand why it's forbidden), so it seems like one of >> two things should be the case: >> >> a. if you can return NIL for clisp and ABCL, it should be possible >> to return NIL for all the other implementations or >> >> b. if returning :unspecific is necessary for some implementations, >> shouldn't returning NIL on CLISP And ABCL fail? >> > I think that in practice, the parent pathname always has NIL in its type, > so that there is no difference between the merged pathname having type > NIL or :UNSPECIFIC. > >> It seems like either these pathnames are never subjected to >> MERGE-PATHNAMES, in which case we can just always return NIL, or they >> /are/ sometimes subjected to MERGE-PATHNAMES, in which case sometimes >> the use of NIL instead of :unspecific will cause oddities (unless the >> default type is always empty). >> > Using :UNSPECIFIC seemed like it might produce more robust code. > But now that I realize the unportability, I don't care as much. > > SBCL, CCL and LispWorks all pass janderson's tests just as well with > either NIL or :UNSPECIFIC. Haven't counted failures in other implementations. > > [ François-René ÐVB Rideau | Reflection&Cybernethics | http://fare.tunes.org ] > Director is a misnomer. You're a hoper. You put all these people together and > you hope it all works out. — Frank Oz, director of "Dirty Rotten Scoundrels" _______________________________________________ asdf-devel mailing list asdf-devel@common-lisp.net http://common-lisp.net/cgi-bin/mailman/listinfo/asdf-devel
