Hi Robert Isn't the :properties slot already there? I just used it (a month ago) to add an ASDF DOCUMENT op to HELambdaP. Worked like a charm once I got the hang of it and it seals the general ASDF machinery from random stuff.
Marco On Thu, Apr 29, 2021 at 6:13 PM Robert Goldman <rpgold...@sift.info> wrote: > ASDF checks to make sure all of the initargs are defined when parsing a > defsystem. This is good for catching errors, but is terrible for > extensibility. This means that any attempt to add additional metadata will > be backwards incompatible. > > I can think of two ways to fix this: > > 1. > > Add a "garbage can" slot to component that will be filled with a > property list, and allow programmers to do whatever they want here. This > doesn't seem great to me. > 2. > > Add a new defsystem parsing error class that is > unknown-component-property, raise it when an unknown property is > encountered and allow the user to continue, discarding the initarg and > accompanying value. > > The second alternative is what I favor. It isn't great, because it will > only maintain extensibility going forward, but I think it's the best we can > do. > > I suppose that we could also add an initarg to tell ASDF to continue such > errors silently. I'd be inclined to suggest that this take an ASDF version > expression as value, so that the error is quietly ignored only by ASDF > versions below that. This means that the property will start to be checked > when it has become authoritative. > > Note that for one's own system and component subclasses, the set of > initargs can be extended without any monkeying around. > -- Marco Antoniotti, Associate Professor tel. +39 - 02 64 48 79 01 DISCo, Università Milano Bicocca U14 2043 http://dcb.disco.unimib.it Viale Sarca 336 http://cdac2021.lakecomoschool.org I-20126 Milan (MI) ITALY
