Custom vs. specifier terminology in lisp/faces.el

I'm currently looking at the relationship of Custom to Mule, primarily with respect to fonts. [Aside to Kyle: I'll keep working on this but I no longer think I'll have code to fix the custom-set-faces bug any time soon. For 21.0, the redefinition of reset-faces looks like the way to go.] Many of the face functions associated with Custom (some of which have leaked into other libraries, such as lisp/faces.el) use terminology different from that documented in Info | Lispref | Specifiers. For example, some functions (eg `face-spec-set') specialize the specifier concept of "locale" to "frame" (in the sense that the argument which represents the specifier's locale is called "frame"; I don't think the semantics are altered at all). In other cases the representation of objects is changed. Eg, specifiers characterize the display with a tag-set [simple list] like `(x color)' while Custom uses alists like `((type x) (class color))'. This use of two different interfaces in lisp/faces.el is quite disconcerting. The functions defined below the comment "used to be in cus-face.el but logically belong [in faces.el]" use a different (but not obviously so and only indirectly documented) interface from the rest of faces.el. It was very tempting to think that the DISPLAY argument was just an alias for TAG-SET, but that's not so. (1) Why does Custom do this with faces? For FSF compatibility? Or is there a technical reason to do it for XEmacs too? The kind of manipulation that Custom does with ordinary properties mostly defeats the purpose of using specifiers, as far as I can see anyway. In particular, this is going to make properly fixing the "custom-set-faces nukes all of Mule's fonts and makes my XEmacs blanch" bug quite complicated---and probably most of it will happen outside the specifier functionality by manipulating those extra properties. Extending Custom faces to handle customizing Mule fonts is going to be even worse, I'm afraid. But specifiers are capable of handling all these problems smoothly, simply by leaving them to work by themselves. Or aren't they? (2) Can the interface of a function like `faces-spec-set' in lisp/faces.el be changed? (It's one of the ones moved from cus-face.el.) I would like it to use the specifier interface (some combination of FACE LOCALE TAG-SET EXACT-P HOW-TO-ADD) but I suspect that that would cause problems in Custom. Would it be a problem to add a (partially redundant) &optional tag-set argument? -- University of Tsukuba Tennodai 1-1-1 Tsukuba 305-8573 JAPAN Institute of Policy and Planning Sciences Telfax: +81 (298) 53-5091 __________________________________________________________________________ __________________________________________________________________________ What are those two straight lines for? "Free software rules."