l...@gnu.org (Ludovic Courtès) writes:
> Hi!
>
> Thanks for the patch.
>
> Andreas Rottmann <a.rottm...@gmx.at> writes:
>
>> This is a prerequisite for the patch implementing SRFI-38, which I'll
>> post next.
>>
>>
>> From: Andreas Rottmann <a.rottm...@gmx.at>
>> Subject: Use a fluid for the list of the reader's "hash procedures"
>>
>> This allows customizing the reader behavior for a dynamic extent more easily.
>>
>> * libguile/read.c (scm_read_hash_procedures): Renamed to
>> `scm_i_read_hash_procedures'.
>> (scm_i_read_hash_procedures_ref, scm_i_read_hash_procedures_set_x):
>> New (internal) accessor functions for the fluid.
>> (scm_read_hash_extend, scm_get_hash_procedure): Use these accessor
>> functions.
>> (scm_init_read): Create the fluid, named `%read-hash-procedures' instead
>> of
>> the previous plain list `read-hash-procedures'.
>
> Hmm that’s an incompatible change. ‘scm_read_hash_procedures’ and
> ‘read-hash-procedures’ aren’t documented, but they’re public.
>
The latter indeed was public -- I've added a compatibility shim,
similiar to the one you suggested. `scm_read_hash_procedures' was
"static", so there should be no issue there.
I kind-of assumed that undocumented functionality would not be held
accountable to the normal deprecation rules. Now that we deprecate the
functionality (and hence implicitly acknowledge that it might still be
in use), I think it might make sense to either:
- Make clear that `%read-hash-procedures' is "internal" -- the name kind
of implies that, but there are quite a few procedures that start with
`%' and are documented in the manual, so I cannot deduce what needs to
be done for a Scheme binding to be marked as internal, at least not
when it is defined in C and has to be accessible to the root module,
and hence is visible in the `(guile-user) module'
- Document `%read-hash-procedures'.
- Mark `%read-hash-procedures' as internal, but offer a documented way
to install a new fluid for a dynamic extent. E.g.:
(define (with-read-hash-extensions extensions thunk)
(with-fluid* %read-hash-procedures (fluid-ref %read-hash-procedures)
(lambda ()
(for-each (lambda (extension)
(read-hash-extend (car extension) (cdr extension)))
extensions)
(thunk))))
> The latter can probably be kept compatible like this:
>
> (begin-deprecated
> (define %deprecated-read-hash-procedures
> (make-procedure-with-setter
> (lambda () (fluid-ref %read-hash-procedures))
> (lambda (v) (fluid-set! %read-hash-procedures v))))
>
> (define-syntax read-hash-procedures
> (lambda (s)
> (syntax-case s ()
> (_ (%deprecated-read-hash-procedures))))))
>
Neat trick, I didn't know about `make-procedure-with-setter'. My patch
now contains equivalent functionality, but only relying on syntax-case,
not `make-procedure-with-setter' -- it turned out you have to use
`make-variable-transformer' or `identifier-syntax' if you want an
identifier macro to work within a `set!' form.
From: Andreas Rottmann <a.rottm...@gmx.at>
Subject: Use a fluid for the list of the reader's "hash procedures"
This allows customizing the reader behavior for a dynamic extent more easily.
* libguile/read.c (scm_read_hash_procedures): Renamed to
`scm_i_read_hash_procedures'.
(scm_i_read_hash_procedures_ref, scm_i_read_hash_procedures_set_x):
New (internal) accessor functions for the fluid.
(scm_read_hash_extend, scm_get_hash_procedure): Use these accessor
functions.
(scm_init_read): Create the fluid, named `%read-hash-procedures' instead of
the previous plain list `read-hash-procedures'.
* test-suite/tests/reader.test: Adapt the "R6RS/SRFI-30 block comment
syntax overridden" test to make use of the fluid.
* module/ice-9/deprecated.scm (read-hash-procedures):
New identifier macro -- backward-compatibility shim.
---
libguile/read.c | 38 ++++++++++++++++++++++++++++----------
module/ice-9/deprecated.scm | 17 ++++++++++++++++-
test-suite/tests/reader.test | 21 ++++++++-------------
3 files changed, 52 insertions(+), 24 deletions(-)
diff --git a/libguile/read.c b/libguile/read.c
index c9219bc..53ab128 100644
--- a/libguile/read.c
+++ b/libguile/read.c
@@ -135,9 +135,21 @@ SCM_DEFINE (scm_read_options, "read-options-interface", 0, 1, 0,
}
#undef FUNC_NAME
-/* An association list mapping extra hash characters to procedures. */
-static SCM *scm_read_hash_procedures;
+/* A fluid referring to an association list mapping extra hash
+ characters to procedures. */
+static SCM *scm_i_read_hash_procedures;
+static inline SCM
+scm_i_read_hash_procedures_ref (void)
+{
+ return scm_fluid_ref (*scm_i_read_hash_procedures);
+}
+
+static inline void
+scm_i_read_hash_procedures_set_x (SCM value)
+{
+ scm_fluid_set_x (*scm_i_read_hash_procedures, value);
+}
/* Token readers. */
@@ -1547,7 +1559,7 @@ SCM_DEFINE (scm_read_hash_extend, "read-hash-extend", 2, 0, 0,
proc, SCM_ARG2, FUNC_NAME);
/* Check if chr is already in the alist. */
- this = *scm_read_hash_procedures;
+ this = scm_i_read_hash_procedures_ref ();
prev = SCM_BOOL_F;
while (1)
{
@@ -1556,8 +1568,9 @@ SCM_DEFINE (scm_read_hash_extend, "read-hash-extend", 2, 0, 0,
/* not found, so add it to the beginning. */
if (scm_is_true (proc))
{
- *scm_read_hash_procedures =
- scm_cons (scm_cons (chr, proc), *scm_read_hash_procedures);
+ SCM new = scm_cons (scm_cons (chr, proc),
+ scm_i_read_hash_procedures_ref ());
+ scm_i_read_hash_procedures_set_x (new);
}
break;
}
@@ -1569,8 +1582,8 @@ SCM_DEFINE (scm_read_hash_extend, "read-hash-extend", 2, 0, 0,
/* remove it. */
if (scm_is_false (prev))
{
- *scm_read_hash_procedures =
- SCM_CDR (*scm_read_hash_procedures);
+ SCM rest = SCM_CDR (scm_i_read_hash_procedures_ref ());
+ scm_i_read_hash_procedures_set_x (rest);
}
else
scm_set_cdr_x (prev, SCM_CDR (this));
@@ -1594,7 +1607,7 @@ SCM_DEFINE (scm_read_hash_extend, "read-hash-extend", 2, 0, 0,
static SCM
scm_get_hash_procedure (int c)
{
- SCM rest = *scm_read_hash_procedures;
+ SCM rest = scm_i_read_hash_procedures_ref ();
while (1)
{
@@ -1738,8 +1751,13 @@ SCM_DEFINE (scm_file_encoding, "file-encoding", 1, 0, 0,
void
scm_init_read ()
{
- scm_read_hash_procedures =
- SCM_VARIABLE_LOC (scm_c_define ("read-hash-procedures", SCM_EOL));
+ SCM read_hash_procs;
+
+ read_hash_procs = scm_make_fluid ();
+ scm_fluid_set_x (read_hash_procs, SCM_EOL);
+
+ scm_i_read_hash_procedures =
+ SCM_VARIABLE_LOC (scm_c_define ("%read-hash-procedures", read_hash_procs));
scm_init_opts (scm_read_options, scm_read_opts);
#include "libguile/read.x"
diff --git a/module/ice-9/deprecated.scm b/module/ice-9/deprecated.scm
index faff234..07ad6d2 100644
--- a/module/ice-9/deprecated.scm
+++ b/module/ice-9/deprecated.scm
@@ -65,7 +65,8 @@
save-stack
named-module-use!
top-repl
- turn-on-debugging))
+ turn-on-debugging
+ read-hash-procedures))
;;;; Deprecated definitions.
@@ -682,3 +683,17 @@ it.")
"Debugging capabilities are present by default.")
(debug-enable 'backtrace)
(read-enable 'positions))
+
+(define (read-hash-procedures-warning)
+ (issue-deprecation-warning
+ "`read-hash-procedures' is deprecated."
+ "Use the fluid `%read-hash-procedures' instead."))
+
+(define-syntax read-hash-procedures
+ (identifier-syntax
+ (_
+ (begin (read-hash-procedures-warning)
+ (fluid-ref %read-hash-procedures)))
+ ((set! _ expr)
+ (begin (read-hash-procedures-warning)
+ (fluid-set! %read-hash-procedures expr)))))
diff --git a/test-suite/tests/reader.test b/test-suite/tests/reader.test
index 6686ca2..0027da7 100644
--- a/test-suite/tests/reader.test
+++ b/test-suite/tests/reader.test
@@ -109,19 +109,14 @@
(pass-if "R6RS/SRFI-30 block comment syntax overridden"
;; To be compatible with 1.8 and earlier, we should be able to override
;; this syntax.
- (let ((rhp read-hash-procedures))
- (dynamic-wind
- (lambda ()
- (read-hash-extend #\| (lambda args 'not)))
- (lambda ()
- (fold (lambda (x y result)
- (and result (eq? x y)))
- #t
- (read-string "(this is #| a comment)")
- `(this is not a comment)))
- (lambda ()
- (set! read-hash-procedures rhp)))))
-
+ (with-fluids ((%read-hash-procedures (fluid-ref %read-hash-procedures)))
+ (read-hash-extend #\| (lambda args 'not))
+ (fold (lambda (x y result)
+ (and result (eq? x y)))
+ #t
+ (read-string "(this is #| a comment)")
+ `(this is not a comment))))
+
(pass-if "unprintable symbol"
;; The reader tolerates unprintable characters for symbols.
(equal? (string->symbol "\x01\x02\x03")
--
tg: (fe15364..) t/read-hash-fluid (depends on: master)
Regards, Rotty
--
Andreas Rottmann -- <http://rotty.yi.org/>
