diff options
Diffstat (limited to 'lisp/emacs-lisp/advice.el')
| -rw-r--r-- | lisp/emacs-lisp/advice.el | 141 |
1 files changed, 15 insertions, 126 deletions
diff --git a/lisp/emacs-lisp/advice.el b/lisp/emacs-lisp/advice.el index 39ea97aa98e..5934975e36a 100644 --- a/lisp/emacs-lisp/advice.el +++ b/lisp/emacs-lisp/advice.el @@ -503,36 +503,6 @@ ;; exact structure of the original argument list as long as the new argument ;; list takes a compatible number/magnitude of actual arguments. -;; @@@ Definition of subr argument lists: -;; ====================================== -;; When advice constructs the advised definition of a function it has to -;; know the argument list of the original function. For functions and macros -;; the argument list can be determined from the actual definition, however, -;; for subrs there is no such direct access available. In Lemacs and for some -;; subrs in Emacs-19 the argument list of a subr can be determined from -;; its documentation string, in a v18 Emacs even that is not possible. If -;; advice cannot at all determine the argument list of a subr it uses -;; `(&rest ad-subr-args)' which will always work but is inefficient because -;; it conses up arguments. The macro `ad-define-subr-args' can be used by -;; the advice programmer to explicitly tell advice about the argument list -;; of a certain subr, for example, -;; -;; (ad-define-subr-args 'fset '(sym newdef)) -;; -;; is used by advice itself to tell a v18 Emacs about the arguments of `fset'. -;; The following can be used to undo such a definition: -;; -;; (ad-undefine-subr-args 'fset) -;; -;; The argument list definition is stored on the property list of the subr -;; name symbol. When an argument list could be determined from the -;; documentation string it will be cached under that property. The general -;; mechanism for looking up the argument list of a subr is the following: -;; 1) look for a definition stored on the property list -;; 2) if that failed try to infer it from the documentation string and -;; if successful cache it on the property list -;; 3) otherwise use `(&rest ad-subr-args)' - ;; @@ Activation and deactivation: ;; =============================== ;; The definition of an advised function does not change until all its advice @@ -1654,41 +1624,6 @@ ;; (fii 3 2) ;; 5 ;; -;; @@ Specifying argument lists of subrs: -;; ====================================== -;; The argument lists of subrs cannot be determined directly from Lisp. -;; This means that Advice has to use `(&rest ad-subr-args)' as the -;; argument list of the advised subr which is not very efficient. In Lemacs -;; subr argument lists can be determined from their documentation string, in -;; Emacs-19 this is the case for some but not all subrs. To accommodate -;; for the cases where the argument lists cannot be determined (e.g., in a -;; v18 Emacs) Advice comes with a specification mechanism that allows the -;; advice programmer to tell advice what the argument list of a certain subr -;; really is. -;; -;; In a v18 Emacs the following will return the &rest idiom: -;; -;; (ad-arglist (symbol-function 'car)) -;; (&rest ad-subr-args) -;; -;; To tell advice what the argument list of `car' really is we -;; can do the following: -;; -;; (ad-define-subr-args 'car '(list)) -;; ((list)) -;; -;; Now `ad-arglist' will return the proper argument list (this method is -;; actually used by advice itself for the advised definition of `fset'): -;; -;; (ad-arglist (symbol-function 'car)) -;; (list) -;; -;; The defined argument list will be stored on the property list of the -;; subr name symbol. When advice looks for a subr argument list it first -;; checks for a definition on the property list, if that fails it tries -;; to infer it from the documentation string and caches it on the property -;; list if it was successful, otherwise `(&rest ad-subr-args)' will be used. -;; ;; @@ Advising interactive subrs: ;; ============================== ;; For the most part there is no difference between advising functions and @@ -2536,52 +2471,11 @@ See Info node `(elisp)Computed Advice' for detailed documentation." If DEFINITION could be from a subr then its NAME should be supplied to make subr arglist lookup more efficient." (require 'help-fns) - (cond - ((or (ad-macro-p definition) (ad-advice-p definition)) - (help-function-arglist (cdr definition))) - (t (help-function-arglist definition)))) - -;; Store subr-args as `((arg1 arg2 ...))' so I can distinguish -;; a defined empty arglist `(nil)' from an undefined arglist: -(defmacro ad-define-subr-args (subr arglist) - `(put ,subr 'ad-subr-arglist (list ,arglist))) -(defmacro ad-undefine-subr-args (subr) - `(put ,subr 'ad-subr-arglist nil)) -(defmacro ad-subr-args-defined-p (subr) - `(get ,subr 'ad-subr-arglist)) -(defmacro ad-get-subr-args (subr) - `(car (get ,subr 'ad-subr-arglist))) - -(defun ad-subr-arglist (subr-name) - "Retrieve arglist of the subr with SUBR-NAME. -Either use the one stored under the `ad-subr-arglist' property, -or try to retrieve it from the docstring and cache it under -that property, or otherwise use `(&rest ad-subr-args)'." - (if (ad-subr-args-defined-p subr-name) - (ad-get-subr-args subr-name) - ;; says jwz: Should use this for Lemacs 19.8 and above: - ;;((fboundp 'subr-min-args) - ;; ...) - ;; says hans: I guess what Jamie means is that I should use the values - ;; of `subr-min-args' and `subr-max-args' to construct the subr arglist - ;; without having to look it up via parsing the docstring, e.g., - ;; values 1 and 2 would suggest `(arg1 &optional arg2)' as an - ;; argument list. However, that won't work because there is no - ;; way to distinguish a subr with args `(a &optional b &rest c)' from - ;; one with args `(a &rest c)' using that mechanism. Also, the argument - ;; names from the docstring are more meaningful. Hence, I'll stick with - ;; the old way of doing things. - (let ((doc (or (ad-real-documentation subr-name t) ""))) - (if (not (string-match "\n\n\\((.+)\\)\\'" doc)) - ;; Signalling an error leads to bugs during bootstrapping because - ;; the DOC file is not yet built (which is an error, BTW). - ;; (error "The usage info is missing from the subr %s" subr-name) - '(&rest ad-subr-args) - (ad-define-subr-args - subr-name - (cdr (car (read-from-string - (downcase (match-string 1 doc)))))) - (ad-get-subr-args subr-name))))) + (help-function-arglist + (if (or (ad-macro-p definition) (ad-advice-p definition)) + (cdr definition) + definition) + 'preserve-names)) (defun ad-docstring (definition) "Return the unexpanded docstring of DEFINITION." @@ -2629,17 +2523,16 @@ definition (see the code for `documentation')." (defun ad-definition-type (definition) "Return symbol that describes the type of DEFINITION." - (if (ad-macro-p definition) - 'macro - (if (ad-subr-p definition) - (if (ad-special-form-p definition) - 'special-form - 'subr) - (if (or (ad-lambda-p definition) - (ad-compiled-p definition)) - 'function - (if (ad-advice-p definition) - 'advice))))) + (cond + ((ad-macro-p definition) 'macro) + ((ad-subr-p definition) + (if (ad-special-form-p definition) + 'special-form + 'subr)) + ((or (ad-lambda-p definition) + (ad-compiled-p definition)) + 'function) + ((ad-advice-p definition) 'advice))) (defun ad-has-proper-definition (function) "True if FUNCTION is a symbol with a proper definition. @@ -3921,10 +3814,6 @@ undone on exit of this macro." ;; Use the advice mechanism to advise `documentation' to make it ;; generate proper documentation strings for advised definitions: -;; This makes sure we get the right arglist for `documentation' -;; during bootstrapping. -(ad-define-subr-args 'documentation '(function &optional raw)) - ;; @@ Starting, stopping and recovering from the advice package magic: ;; =================================================================== |