MulDoc extends ElDoc and makes function definition very easy.

ElDoc is a minor mode to show documentation in echo area. ElDoc function is implemented for several languages besides Emacs Lisp.

MulDoc solves ElDoc problem.

• ElDoc can usually only register one or two functions.
• ElDoc implementations are difficult to understand and tends to be untestable.

MulDoc has APIs for end users and Lisp package developers.

Note: no end-user MulDoc implementation yet.

(defunmy-foo-mode-setup () "Setup function for `foo-mode'." (muldoc-mode 1) (push muldoc-documentation-functions #'muldoc-foo) (push muldoc-documentation-functions #'muldoc-html)) (with-eval-after-load"foo-mode" (add-hook'foo-mode-hook'my-foo-mode-setup))

(defcustomfoo-muldoc-function-form '(return-type "" function "(" (params ", ":type"":name) ")") "MulDoc display format for Foo function call.":group'muldoc-foo:type'sexp) (define-muldoc foo-muldoc-func "MulDoc function for Foo language.";; This function is extremely simplified, but represents the specification of;; the value that an actual implementation should return. (muldoc-list foo-muldoc-function-form :params '((:type"string":name"message")) :current-param0:values (list:function"print")))

Actually the DSL is just a list. Its structure is (cons form plist).

form is a notation for converting a list to a string.

• \"string\": Just combined with that value.
• :keyword: The value passed as a keyword in plist.
• symbol: Symbol is evaluated as a variable name.
• (params separator &optional param-info): This looks like a function, but combines :params with separator.
  • separator: In languages similar to C, ", " is assumed.
  • paraminfo: A plist for parameters.
• (eval ...): The expression following eval is evaluated as Emacs Lisp.
• (if cond then ...else), (when cond ...body), (unless cond ...body): Same as Emacs Lisp.
• Any other list is evaluated as a Emacs Lisp expression.

It is an Property List with the following keys.

• :params: List of string or plist.
• :current-param: 0-origin current position of argument list.

This macro is very similar to defun. It’s actually just a defun wrapper, but it is responsible for converting between MulDoc DSL and ElDoc output formats.