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authorAndy Wingo <wingo@pobox.com>2009-01-27 13:43:07 +0100
committerAndy Wingo <wingo@pobox.com>2009-01-28 12:12:29 +0100
commit8b8b59969445bd8faee53f1ae0a16391365dfe51 (patch)
tree555632e8094737f42372e454498dd093495d2021
parent94922b177bd2cb26a018a7605d4567701b2279b8 (diff)
downloadguile-8b8b59969445bd8faee53f1ae0a16391365dfe51.tar.gz
merge in from guile-lib: add some extensibility to `help'
* ice-9/session.scm (add-value-help-handler!) (remove-value-help-handler!, add-name-help-handler!) (remove-name-help-handler!): New public interfaces, to allow some basic extensibility of the help interface. Merged in from guile-lib's (scheme session).
-rw-r--r--ice-9/session.scm72
1 files changed, 64 insertions, 8 deletions
diff --git a/ice-9/session.scm b/ice-9/session.scm
index 1c9f48016..6971a7894 100644
--- a/ice-9/session.scm
+++ b/ice-9/session.scm
@@ -20,12 +20,61 @@
:use-module (ice-9 documentation)
:use-module (ice-9 regex)
:use-module (ice-9 rdelim)
- :export (help apropos apropos-internal apropos-fold
- apropos-fold-accessible apropos-fold-exported apropos-fold-all
- source arity system-module))
+ :export (help
+ add-value-help-handler! remove-value-help-handler!
+ add-name-help-handler! remove-name-help-handler!
+ apropos apropos-internal apropos-fold apropos-fold-accessible
+ apropos-fold-exported apropos-fold-all source arity
+ system-module module-commentary))
+(define *value-help-handlers* '())
+
+(define (add-value-help-handler! proc)
+ "Adds a handler for performing `help' on a value.
+
+`proc' will be called as (PROC NAME VALUE). `proc' should return #t to
+indicate that it has performed help, a string to override the default
+object documentation, or #f to try the other handlers, potentially
+falling back on the normal behavior for `help'."
+ (set! *value-help-handlers* (cons proc *value-help-handlers*)))
+
+(define (remove-value-help-handler! proc)
+ "Removes a handler for performing `help' on a value.
+
+See the documentation for `add-value-help-handler' for more
+information."
+ (set! *value-help-handlers* (delete! proc *value-help-handlers*)))
+
+(define (try-value-help name value)
+ (or-map (lambda (proc) (proc name value)) *value-help-handlers*))
+
+
+(define *name-help-handlers* '())
+
+(define (add-name-help-handler! proc)
+ "Adds a handler for performing `help' on a name.
+
+`proc' will be called with the unevaluated name as its argument. That is
+to say, when the user calls `(help FOO)', the name is FOO, exactly as
+the user types it.
+
+The return value of `proc' is as specified in
+`add-value-help-handler!'."
+ (set! *name-help-handlers* (cons proc *name-help-handlers*)))
+
+(define (remove-name-help-handler! proc)
+ "Removes a handler for performing `help' on a name.
+
+See the documentation for `add-name-help-handler' for more
+information."
+ (set! *name-help-handlers* (delete! proc *name-help-handlers*)))
+
+(define (try-name-help name)
+ (or-map (lambda (proc) (proc name)) *name-help-handlers*))
+
+
;;; Documentation
;;;
(define help
@@ -45,6 +94,10 @@ You don't seem to have regular expressions installed.\n"))
type x))))
(cond
+ ;; User-specified
+ ((try-name-help name)
+ => (lambda (x) (if (not (eq? x #t)) (display x))))
+
;; SYMBOL
((symbol? name)
(help-doc name
@@ -60,10 +113,12 @@ You don't seem to have regular expressions installed.\n"))
((and (list? name)
(= (length name) 2)
(eq? (car name) 'unquote))
- (cond ((object-documentation
- (local-eval (cadr name) env))
- => write-line)
- (else (not-found 'documentation (cadr name)))))
+ (let ((value (local-eval (cadr name) env)))
+ (cond ((try-value-help (cadr name) value)
+ => noop)
+ ((object-documentation value)
+ => write-line)
+ (else (not-found 'documentation (cadr name))))))
;; (quote SYMBOL)
((and (list? name)
@@ -109,7 +164,8 @@ You don't seem to have regular expressions installed.\n"))
(let ((entries (apropos-fold (lambda (module name object data)
(cons (list module
name
- (object-documentation object)
+ (or (try-value-help name object)
+ (object-documentation object))
(cond ((closure? object)
"a procedure")
((procedure? object)