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Re: stack overflow equal? values
From: |
Kevin Ryde |
Subject: |
Re: stack overflow equal? values |
Date: |
Fri, 19 Jan 2007 09:42:17 +1100 |
User-agent: |
Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) |
address@hidden (Ludovic Courtès) writes:
>
> I propose the following simple fix. Ok to apply?
Yep, looks good.
After I posted I wondered if the values struct is an actual "s" or if
there's some strange extra I couldn't spot. Testing eq avoids
worrying about that.
Dunno why values are a struct and not a smob cell.
> Actually, `scm_i_struct_equalp ()' should also compare the "tail
> elements" (when there are tail elements),
Yes.
> but their semantics are a
> little fuzzy to me. In particular, I don't understand why the size of
> the tail array can be specified in both `make-vtable-vtable' and
> `make-struct': What does that mean? Which one should really be taken
> into account?
Dunno :).
> It seems that the code is a bit unclear on this too:
>
> guile> (define v (make-vtable-vtable "pr" 0))
> guile> (define s (make-struct v 123))
> guile> (struct-ref s 10)
> Segmentation fault
A segv is a bug, obviously, whichever way it's actually meant to be.
> (Looks like the API is so complex that few people actually bothered to
> use it to its full extents. ;-))
The records level is friendlier I guess. For a long time I couldn't
understand what "vtable" meant, I still don't think I quite do. Maybe
the docs should be tweaked, to help show what structs are typically
meant to be.
> --- orig/test-suite/tests/structs.test
> +++ mod/test-suite/tests/structs.test
> @@ -82,12 +82,18 @@
> (set-owner! ball "Bill")
> (string=? (owner ball) "Bill")))
>
> - (pass-if "equal?"
You can make a with-test-prefix group if you like. An exercise of an
actual values too will be good, maybe in eval.test.