Hi Neil, Note: I reply to messages in order of least difficulty. ;-)
Neil Jerram <n...@ossau.uklinux.net> writes: > l...@gnu.org (Ludovic Courtès) writes: >> For these reasons, we may want to merge this patch in `master' as >> well. > > Yes, I think so. Noted, will do. >> 2. The second step does the actual work [1]. Currently, it only >> deals with subrs, i.e., primitive procedures with "relatively few" >> arguments (see `create_gsubr ()'). > > Presumably that is in practice almost all of the primitives, though? That's 200 gsubrs, vs. 873 "simple" subrs. >> To distinguish subrs (few arguments) from gsubrs (unrestricted >> arity, see `default:' in `create_gsubr ()'), a Dirty Hack(tm) was >> needed. The hack is that `SCM_DEFINE' is an alias for a new macro >> `SCM_DEFINE_SUBR_reqX_optY_rstZ', where X, Y and Z are the number >> of required, optional and rest arguments. If X, Y and Z are such >> that a raw subr can be used, then the macro is an alias for >> `SCM_DEFINE_SUBR', which does the actual static allocation; >> otherwise, it's an alias for `SCM_DEFINE_GSUBR', which is the same >> as `SCM_DEFINE' in `master'. > > Not so bad, IMO. It breaks cases like primitive procedures with more than 16 arguments (because I arbitrarily decided that `snarf-gsubr.h' would contain definitions up to 16 req/opt args), and situations like: SCM_DEFINE (scm_foo, "foo", 0001, 0002, 0003, ...) This is probably acceptable in practice. >> The dirtiest part of the hack is the generation of "snarf-gsubr.h" >> which contains definitions of `SCM_DEFINE_SUBR_reqX_optY_rstZ' for >> a "reasonable" number of combinations of X, Y and Z (C++ template >> specialization would solve this problem much more elegantly...). > > This part is quite dirty, as you say. I'm not sure what's the > advantage of the generation at make time. Wouldn't it be simpler, and > have the same function, just to hardcode all these definitions > directly in snarf.h? Given the size of `snarf-gsubr.h' (there are 16 * 16 * 2 = 512 combinations), I'd rather keep it separated. The makefile rule is an efficient way to compress it. ;-) >> [0] >> http://git.savannah.gnu.org/gitweb/?p=guile.git;a=commitdiff;h=2ee5aa25dbd679b175707762f5961585027e1397 > > Should probably remove the comments about how many subrs there are, > since it's no longer relevant. Right. > I see there's no NEWS in the commit; is that because there's no impact > on the API? Even if so, I imagine it might merit a line in the 2.0 > release notes. If you agree, I'd encourage you to write the NEWS now, > rather than adding it later. Right. It's just that I have not maintained any NEWS file for BDW-GC-related changes, initially. > + meta_info = scm_gc_malloc (2 * sizeof (* meta_info), > + "subr meta-info"); > > I found the space between "*" and "meta_info" confusing for a few > seconds, so would have a preference for "*meta_info". Yes, I feel the same today (I probably felt differently that day). :-) >> [1] >> http://git.savannah.gnu.org/gitweb/?p=guile.git;a=commitdiff;h=46f9baf49a8ea4461e8494c75a88b87d0f5c5195 > > Why does the macro code sometimes use scm_i_paste, and sometimes ## > directly? The `scm_i_paste ()' macro is needed so that macro-expansion of definitions like those of `srfi-4.i.c' work as expected. There are a few cases where it isn't used (e.g., in `SCM_IMMUTABLE_DOUBLE_CELL ()'), but I guess it didn't cause any problem because `scm_i_paste ()' was properly used by callers. We could unify that but `scm_i_paste ()' has the drawback of having a long name. > Finally SCM_SUBR_ARITY_TO_TYPE... The implementation feels a bit > messy, but I don't have any alternative to suggest, so I guess that's > OK. The problem is that this information is shared among 3 places: `SCM_SUBR_ARITY_TO_TYPE ()', `create_gsubr ()', and `SCM_DEFINE_SUBR_reqX_optY_rstZ ()'. Ideally, all 3 would be generated from a single source. Besides, I think we need to review the use of subr/gsubr tag in detail to see whether we can make better use of them. > But what about the fact that it's added to the libguile API? I > realize that this is necessary to some extent so that snarf.h can be > used by application code - but can we somehow restrict > SCM_SUBR_ARITY_TO_TYPE to being used in that context, so that it > doesn't become on ongoing constraint for us? I share your concern, but I have no idea of how to avoid it. We could add `_I_' in its name, perhaps. Hopefully, it's too low-level for anyone to try it. Thanks, Ludo'.
