>> 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
