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-rw-r--r--ice-9/session.scm67
1 files changed, 59 insertions, 8 deletions
diff --git a/ice-9/session.scm b/ice-9/session.scm
index 1c9f48016..c1bbab206 100644
--- a/ice-9/session.scm
+++ b/ice-9/session.scm
@@ -20,12 +20,58 @@
: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*
+ `(,(lambda (name value)
+ (object-documentation value))))
+
+(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."
+ (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.
+
+`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! *name-help-handlers* (cons proc *name-help-handlers*)))
+
+(define (remove-name-help-handler! proc)
+ "Removes a handler for performing `help' on a name."
+ (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 +91,10 @@ 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 +110,11 @@ 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 ((doc (try-value-help (cadr name)
+ (local-eval (cadr name) env))))
+ (cond ((not doc) (not-found 'documentation (cadr name)))
+ ((eq? doc #t)) ;; pass
+ (else (write-line doc)))))
;; (quote SYMBOL)
((and (list? name)
@@ -109,7 +160,7 @@ 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)
+ (try-value-help name object)
(cond ((closure? object)
"a procedure")
((procedure? object)