Re: dynamic-completion-table

[Roland Winkler]

On Wed Jun 25 2003 Richard Stallman wrote:
>       "Use function FUN as a dynamic completion table.
>     FUN is called with one argument, the string for which
>     completion is required, and it should return an alist
>     containing all the intended possible completions.
> 
> Is FUN required to return only the possible completions of that
> string, or can it ignore the string and always return the full list of
> possibilities?  Looking at the code, I think it can ignore the string.
> The doc string should say so.
> 
> Both macros seem useful--you can install them.

Stefan,

Could you please do that for me? Thank you very much!
I hope that the docstring of dynamic-completion-table is now OK.

(defmacro dynamic-completion-table (fun)
  "Use function FUN as a dynamic completion table.
FUN is called with one argument, the string for which completion is required,
and it should return an alist containing all the intended possible
completions. This alist may be a full list of possible completions so that FUN
can ignore the value of its argument. If completion is performed in the
minibuffer, FUN will be called in the buffer from which the minibuffer was
entered. `dynamic-completion-table' then computes the completion, see Info
node `(elisp)Programmed Completion'."
  (let ((win (make-symbol "window"))
        (string (make-symbol "string"))
        (predicate (make-symbol "predicate"))
        (mode (make-symbol "mode")))
    `(lambda (,string ,predicate ,mode)
       (with-current-buffer (let ((,win (minibuffer-selected-window)))
                              (if (window-live-p ,win) (window-buffer ,win)
                                (current-buffer)))
         (cond
          ((eq ,mode t) (all-completions ,string (,fun ,string) ,predicate))
          ((not ,mode) (try-completion ,string (,fun ,string) ,predicate))
          (t (test-completion ,string (,fun ,string) ,predicate)))))))

(defmacro lazy-completion-table (var fun &rest args)
  "Initialize variable VAR as a lazy completion table.
If the completion table VAR is used for the first time (e.g., by passing VAR
as an argument to `try-completion'), the function FUN is called with arguments
ARGS. FUN must return the completion table that will be stored in VAR. If
completion is requested in the minibuffer, FUN will be called in the buffer
from which the minibuffer was entered. The return value of
`lazy-completion-table' must be used to initialize the value of VAR."
  (let ((str (make-symbol "string")))
    `(dynamic-completion-table
      (lambda (,str)
        (unless (listp ,var)
          (setq ,var (funcall ',fun ,@args)))
        ,var))))


> Don't forget to mention them in etc/NEWS.

The following should be put into etc/NEWS:

*** The new macro dynamic-completion-table supports using functions
as a dynamic completion table.

  (dynamic-completion-table FUN)

FUN is called with one argument, the string for which completion is required,
and it should return an alist containing all the intended possible
completions. This alist may be a full list of possible completions so that FUN
can ignore the value of its argument. If completion is performed in the
minibuffer, FUN will be called in the buffer from which the minibuffer was
entered. dynamic-completion-table then computes the completion.

*** The new macro lazy-completion-table initializes a variable
as a lazy completion table.

  (lazy-completion-table VAR FUN &rest ARGS)

If the completion table VAR is used for the first time (e.g., by passing VAR
as an argument to `try-completion'), the function FUN is called with arguments
ARGS. FUN must return the completion table that will be stored in VAR. If
completion is requested in the minibuffer, FUN will be called in the buffer
from which the minibuffer was entered. The return value of
`lazy-completion-table' must be used to initialize the value of VAR.




Roland