racket/class: add `dynamic-send'

collects/racket/private/class-internal.rkt

@@ -36,7 +36,8 @@
            object% object? externalizable<%> printable<%> writable<%> equal<%>
            object=?
            new make-object instantiate
-           send send/apply send/keyword-apply send* class-field-accessor class-field-mutator with-method
+           send send/apply send/keyword-apply send* dynamic-send
+           class-field-accessor class-field-mutator with-method
            get-field set-field! field-bound? field-names
            private* public*  pubment*
            override* overment*
@@ -3853,6 +3854,13 @@
      ;; send/keyword-apply
      send/keyword-apply)))
 
+(define dynamic-send
+  (make-keyword-procedure
+   (lambda (kws kw-vals obj method-name . args)
+     (unless (object? obj) (raise-type-error 'dynamic-send "object" obj))
+     (unless (symbol? method-name) (raise-type-error 'dynamic-send "symbol" method-name))
+     (keyword-apply (find-method/who 'dynamic-send obj method-name) kws kw-vals obj args))))
+
 (define-syntaxes (send* send*-traced)
   (let* ([core-send*
           (lambda (traced?)
@@ -4818,7 +4826,8 @@
          object% object? object=? externalizable<%> printable<%> writable<%> equal<%>
          new make-object instantiate
          get-field set-field! field-bound? field-names
-         send send/apply send/keyword-apply send* class-field-accessor class-field-mutator with-method
+         send send/apply send/keyword-apply send* dynamic-send
+         class-field-accessor class-field-mutator with-method
          private* public*  pubment*
          override* overment*
          augride* augment*

collects/scribblings/reference/class.scrbl

@@ -1105,6 +1105,15 @@ be any expression.}
 Like @racket[send/apply], but with expressions for keyword and
 argument lists like @racket[keyword-apply].}
 
+@defproc[(dynamic-send [obj object?] 
+                       [method-name symbol?]
+                       [v any/c] ...
+                       [#:<kw> kw-arg any/c] ...) any]{
+
+Calls the method on @racket[obj] whose name matches
+@racket[method-name], passing along all given @racket[v]s and
+@racket[kw-arg]s.}
+
 
 @defform/subs[(send* obj-expr msg ...)
               ([msg (method-id arg ...)

collects/tests/racket/object.rktl

@@ -793,6 +793,12 @@
 (test '(2 12) 'dotted (send/keyword-apply dotted h null null (list 2)))
 (test '(3 8) 'dotted (send/keyword-apply dotted h '(#:y) (list 8) (list 3)))
 
+(test '(c b a) dynamic-send dotted 'f 'a 'b 'c)
+(test '(c b a) apply dynamic-send dotted 'f 'a '(b c))
+(test '(e 12) apply dynamic-send dotted 'h '(e))
+(test '(f 13) 'dotted (apply dynamic-send dotted 'h '(f) #:y 13))
+(test '(g 14) keyword-apply dynamic-send '(#:y) '(14) dotted 'h '(g))
+
 (syntax-test #'(send/apply dotted f 2 . l))
 
 ;; ------------------------------------------------------------

doc/release-notes/racket/HISTORY.txt

@@ -4,6 +4,7 @@ Regexps are `equal?' when they have the same source [byte] string
 Numbers, characters, strings, byte strings, and regexps are interned by
  read and datum->syntax
 Added read-intern-literal
+racket/class: added send/keyword-apply and dynamic-send
 racket/draw: added get-names to color-database<%>
 mzlib/pconvert: added add-make-prefix-to-constructor parameter,
  which changes the default constructor-style printing in DrRacket