Re: Use DEFAULT argument to completing-read

Andy> How many packages are actually likely to get feature creep Andy> that is backwardsly incompatible? It depends on how far back you want to be compatible. Also whether the particular creeping feature was used by the package in question before. I think it's very difficult to assess ex ante, but we have seen these problems already. I think the mule-base problems with setting environment are indicative of the kind of problems you can run into. Emacs Lisp has never really had a module concept, so APIs are a sometime thing. I know that the ETL Mule developers have never really hesitated to change de facto APIs and then fix things that break. And we spend significant effort synching with the FSF's Emacs; a lot of this is due to the fact that APIs are evolved, not defined, rather than actual new functionality. Also, people who for whatever reason are using an old XEmacs might want to use a newly-released package. This didn't use to really be a problem, since people who went off, downloaded, installed, and customized new libraries in their .emacs were pretty sophisticated. But the package-user interface makes this a lot easier. Andy> It seems to me you could pick a small subset (mule-base, Andy> xemacs-base?) of packages that you want to tie to a specific Andy> major number whilst letting the others freefall. If it's really an issue of _tie_ then they should not be packages, they should be in the core. I think package installation should normally check for XEmacs version on an relatively advisory basis, eg "Warning: this package was developed under XEmacs 21.8 and using it with an earlier version of XEmacs or with a non-XEmacs GNU Emacs is untested and may involve some breakage." In general, at run-time packages should rather be doing (require 'feature); it's only where APIs change that a warning is needed. If breakage is actually reported, the package maintainer would have the choice of fixing the breakage or upgrading the warning from "untested and may involve some breakage" to "unsupported and has been reported to involve significant breakage; you should only install this package if you are willing to deal with that breakage yourself." -- University of Tsukuba Tennodai 1-1-1 Tsukuba 305-8573 JAPAN Institute of Policy and Planning Sciences Tel/fax: +81 (298) 53-5091 _________________ _________________ _________________ _________________ What are those straight lines for? "XEmacs rules."