read-from-minibuffer and friends.

read-from-minibuffer and friends.

[Luc Teirlinck]

I am currently reading minibuf.texi.  There is a small inconsistency
between the description of the functions `read-no-blanks-input',
`read-minibuffer' and `eval-minibuffer' in the Elisp manual and their
actual behavior.  For all three functions it is claimed that the
optional argument INITIAL behaves exactly like in read-from-minibuffer.
This is incorrect.  Hence the claim that these functions are equivalent
to the Elisp code displayed in `(elisp)Text from Minibuffer' and
`(elisp)Object from Minibuffer' is not 100% accurate either.  As the
ielm run below shows, INITIAL _has_ to be a string or nil for the
three mentioned functions, but is, in addition, allowed to be a cons
of a string and an integer for `read-from-minibuffer' (and
`read-string').

The "Usage note" in `(elisp)Text from Minibuffer', nearly "deprecates"
INITIAL, so that probably there is no need to conform the three
functions to read-from-minibuffer's behavior.  I will point out the
subtlety in the Elisp manual, but first I want to make sure that it
_really_ is the documentation that needs to be changed and not the
code itself.

Ielm run illustrating this:

===File ~/minibuf-ielm======================================
*** Welcome to IELM ***  Type (describe-mode) for help.
ELISP> (read-from-minibuffer "Prompt: " '("123456789" . 3))
"123456789"
ELISP> (read-string "Prompt: " '("123456789" . 3))
"123456789"
ELISP> (read-no-blanks-input "Prompt: " '("123456789" . 3))
*** Eval error ***  Wrong type argument: stringp, ("123456789" . 3)
ELISP> (read-minibuffer "Prompt: " '("123456789" . 3))
*** Eval error ***  Wrong type argument: stringp, ("123456789" . 3)
ELISP> (eval-minibuffer "Prompt: " '("123456789" . 3))
*** Eval error ***  Wrong type argument: stringp, ("123456789" . 3)
ELISP> (read-no-blanks-input "Prompt: " "123456789")
"123456789"
ELISP> (read-minibuffer "Prompt: " "123456789")
123456789
ELISP> (eval-minibuffer "Prompt: " "123456789")
123456789
ELISP> 
============================================================

Re: read-from-minibuffer and friends.

[Richard Stallman]

INITIAL is not quite deprecated.  It is still used by a few things
and we don't plan to change them.

I think ideally all these functions should handle INITIAL
in the same way.  If it is easy to do that, please do it.
I would guess the best way is to move the handling of INITIAL
from Fread_from_minibuffer into read_minibuf.

But that's not worth a lot of work.  If that turns out to have snags,
then the fallback is to document the current behavior.

Re: read-from-minibuffer and friends.

[Luc Teirlinck]

Richard Stallman wrote:

   I think ideally all these functions should handle INITIAL
   in the same way.  If it is easy to do that, please do it.
   I would guess the best way is to move the handling of INITIAL
   from Fread_from_minibuffer into read_minibuf.

I did exactly that.  `read_minibuf' only does something different
after my changes in cases where it threw an error before, so there
should be no danger of breaking existing code.  I still will check a
few details before sending a patch.

Sincerely,

Luc.

Re: read-from-minibuffer and friends.

[Luc Teirlinck]

Richard Stallman wrote:

   I think ideally all these functions should handle INITIAL
   in the same way.  If it is easy to do that, please do it.
   I would guess the best way is to move the handling of INITIAL
   from Fread_from_minibuffer into read_minibuf.

Attached is a patch that does exactly that.  `read_minibuf' only does
something different after the patch in cases where it threw an error
before, so there should be no danger of breaking existing code.  If
the patch seems OK, I could install it as soon as Savannah starts
functioning again.

===File ~/minibuf.c-diff====================================
*** minibuf.c.~1.262.~	Wed Nov  5 22:05:19 2003
--- minibuf.c	Sun Dec 14 10:39:56 2003
***************
*** 404,413 ****
    return make_buffer_string (prompt_end, PT, 1);
  }
  \f
! /* Read from the minibuffer using keymap MAP, initial contents INITIAL
!    (a string), putting point minus BACKUP_N bytes from the end of INITIAL,
     prompting with PROMPT (a string), using history list HISTVAR
!    with initial position HISTPOS.  (BACKUP_N should be <= 0.)
  
     Normally return the result as a string (the text that was read),
     but if EXPFLAG is nonzero, read it and return the object read.
--- 404,418 ----
    return make_buffer_string (prompt_end, PT, 1);
  }
  \f
! /* Read from the minibuffer using keymap MAP and initial contents INITIAL,
!    putting point minus BACKUP_N bytes from the end of INITIAL,
     prompting with PROMPT (a string), using history list HISTVAR
!    with initial position HISTPOS.  INITIAL should be a string or a
!    cons of a string and an integer.  BACKUP_N should be <= 0, or
!    Qnil, which is equivalent to 0.  If INITIAL is a cons, BACKUP_N is
!    ignored and replaced with an integer that puts point N characters
!    from the beginning of INITIAL, where N is the CDR of INITIAL, or at
!    the beginning of INITIAL if N <= 0.
  
     Normally return the result as a string (the text that was read),
     but if EXPFLAG is nonzero, read it and return the object read.
***************
*** 419,425 ****
  
     If ALLOW_PROPS is nonzero, we do not throw away text properties.
  
!    if INHERIT_INPUT_METHOD is nonzeor, the minibuffer inherit the
     current input method.  */
  
  static Lisp_Object
--- 424,430 ----
  
     If ALLOW_PROPS is nonzero, we do not throw away text properties.
  
!    if INHERIT_INPUT_METHOD is nonzero, the minibuffer inherits the
     current input method.  */
  
  static Lisp_Object
***************
*** 441,446 ****
--- 446,452 ----
    Lisp_Object mini_frame, ambient_dir, minibuffer, input_method;
    struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5;
    Lisp_Object enable_multibyte;
+   int pos = INTEGERP (backup_n) ? XINT (backup_n) : 0;
  
    /* String to add to the history.  */
    Lisp_Object histstring;
***************
*** 456,461 ****
--- 462,488 ----
      cancel_hourglass ();
  #endif
  
+   if (!NILP (initial))
+     {
+       if (CONSP (initial))
+ 	{
+ 	  backup_n = Fcdr (initial);
+ 	  initial = Fcar (initial);
+ 	  CHECK_STRING (initial);
+ 	  if (!NILP (backup_n))
+ 	    {
+ 	      CHECK_NUMBER (backup_n);
+ 	      /* Convert to distance from end of input.  */
+ 	      if (XINT (backup_n) < 1)
+ 		/* A number too small means the beginning of the string.  */
+ 		pos =  - SCHARS (initial);
+ 	      else
+ 		pos = XINT (backup_n) - 1 - SCHARS (initial);
+ 	    }
+ 	}
+       else
+ 	CHECK_STRING (initial);
+     }
    val = Qnil;
    ambient_dir = current_buffer->directory;
    input_method = Qnil;
***************
*** 482,488 ****
  
    if (noninteractive)
      {
!       val = read_minibuf_noninteractive (map, initial, prompt, backup_n,
  					 expflag, histvar, histpos, defalt,
  					 allow_props, inherit_input_method);
        UNGCPRO;
--- 509,516 ----
  
    if (noninteractive)
      {
!       val = read_minibuf_noninteractive (map, initial, prompt,
! 					 make_number (pos),
  					 expflag, histvar, histpos, defalt,
  					 allow_props, inherit_input_method);
        UNGCPRO;
***************
*** 633,640 ****
    if (!NILP (initial))
      {
        Finsert (1, &initial);
!       if (INTEGERP (backup_n))
! 	Fforward_char (backup_n);
      }
  
    clear_message (1, 1);
--- 661,667 ----
    if (!NILP (initial))
      {
        Finsert (1, &initial);
!       Fforward_char (make_number (pos));
      }
  
    clear_message (1, 1);
***************
*** 884,891 ****
    which INITIAL-CONTENTS corresponds to).
    Positions are counted starting from 1 at the beginning of the list.
  Sixth arg DEFAULT-VALUE is the default value.  If non-nil, it is available
!  for history commands; but `read-from-minibuffer' does NOT return DEFAULT-VALUE
!  if the user enters empty input!  It returns the empty string.
  Seventh arg INHERIT-INPUT-METHOD, if non-nil, means the minibuffer inherits
   the current input method and the setting of `enable-multibyte-characters'.
  If the variable `minibuffer-allow-text-properties' is non-nil,
--- 911,919 ----
    which INITIAL-CONTENTS corresponds to).
    Positions are counted starting from 1 at the beginning of the list.
  Sixth arg DEFAULT-VALUE is the default value.  If non-nil, it is available
!   for history commands; but, unless READ is non-nil, `read-from-minibuffer'
!   does NOT return DEFAULT-VALUE if the user enters empty input!  It returns
!   the empty string.
  Seventh arg INHERIT-INPUT-METHOD, if non-nil, means the minibuffer inherits
   the current input method and the setting of `enable-multibyte-characters'.
  If the variable `minibuffer-allow-text-properties' is non-nil,
***************
*** 895,927 ****
       Lisp_Object prompt, initial_contents, keymap, read, hist, default_value;
       Lisp_Object inherit_input_method;
  {
-   int pos = 0;
    Lisp_Object histvar, histpos, position, val;
    struct gcpro gcpro1;
  
-   position = Qnil;
- 
    CHECK_STRING (prompt);
-   if (!NILP (initial_contents))
-     {
-       if (CONSP (initial_contents))
- 	{
- 	  position = Fcdr (initial_contents);
- 	  initial_contents = Fcar (initial_contents);
- 	}
-       CHECK_STRING (initial_contents);
-       if (!NILP (position))
- 	{
- 	  CHECK_NUMBER (position);
- 	  /* Convert to distance from end of input.  */
- 	  if (XINT (position) < 1)
- 	    /* A number too small means the beginning of the string.  */
- 	    pos =  - SCHARS (initial_contents);
- 	  else
- 	    pos = XINT (position) - 1 - SCHARS (initial_contents);
- 	}
-     }
- 
    if (NILP (keymap))
      keymap = Vminibuffer_local_map;
    else
--- 923,932 ----
***************
*** 944,950 ****
  
    GCPRO1 (default_value);
    val = read_minibuf (keymap, initial_contents, prompt,
! 		      make_number (pos), !NILP (read),
  		      histvar, histpos, default_value,
  		      minibuffer_allow_text_properties,
  		      !NILP (inherit_input_method));
--- 949,955 ----
  
    GCPRO1 (default_value);
    val = read_minibuf (keymap, initial_contents, prompt,
! 		      Qnil, !NILP (read),
  		      histvar, histpos, default_value,
  		      minibuffer_allow_text_properties,
  		      !NILP (inherit_input_method));
***************
*** 960,967 ****
       Lisp_Object prompt, initial_contents;
  {
    CHECK_STRING (prompt);
-   if (!NILP (initial_contents))
-     CHECK_STRING (initial_contents);
    return read_minibuf (Vminibuffer_local_map, initial_contents,
  		       prompt, Qnil, 1, Qminibuffer_history,
  		       make_number (0), Qnil, 0, 0);
--- 965,970 ----
***************
*** 1012,1020 ****
       Lisp_Object prompt, initial, inherit_input_method;
  {
    CHECK_STRING (prompt);
-   if (! NILP (initial))
-     CHECK_STRING (initial);
- 
    return read_minibuf (Vminibuffer_local_ns_map, initial, prompt, Qnil,
  		       0, Qminibuffer_history, make_number (0), Qnil, 0,
  		       !NILP (inherit_input_method));
--- 1015,1020 ----
============================================================