RE: completing-read does not accept spaces

[Drew Adams <drew.adams@oracle.com>]

> >> Reading the docstring of completing-read I see no reason why it should
> >> not accept spaces. So either the docstring is at fault or there is a bug
> >> on completing-read.
> >
> > No.  The doc to read is (elisp) `Completion Commands', in particular,
> > about the variables named `minibuffer-local-*-map'.
> 
> This is terrible. completing-read docstring says
>
>    Read a string in the minibuffer, with completion.
> 
> A string is a string is a string. It doesn't say "a word", or "a
> symbol", or "a string without spaces". It says "a string".

It should perhaps say something like "Read your input in the minibuffer
with completion, and return a string."

It says "a string" because that is what `completing-read' returns.

But if you find that doc string confusing, then by all means, consider
filing a doc bug.  

> >> Curiously, the function will complete the user's input to a string
> >> containing spaces if there is one on the collection of candidates:
> >> (completing-read "say: " (list "hello there"))
> >
> > Irrelevant here.  As the doc I mentioned says, `SPC' is bound to
> > `minibuffer-complete-word', and that is what you are seeing.  `SPC' is
> > not bound to `self-insert-command' here - it is not inserting itself.
> 
> So by not binding SPC to self-insert-command they are breaking
> completing-read stated purpose.

The purpose as stated does not say anything about what keys you can type
to produce the minibuffer content that gets read.

> > It is just completing a "word" at a time.
> >
> >> Please submit a bug report (M-x report-emacs-bug) against completing-
> >> read.
> >
> > No.  There is no bug here.  This is the behavior by design, like
> > it or not.
> 
> The docstring is wrong when it says "Read a string". That's a bug, IMO.

See above.  The input part of the minibuffer (i.e., after the prompt)
can be said to be read as a string.  But even that is not necessarily
accurate.  It is certainly not simply read as a Lisp string, in the
sense of what function `read' does.

But really, I believe what is intended by "Read a string" here is that
the minibufer content is possibly completed and then is accepted and
interpreted.  IOW, this use of "read" is in the general sense of
_reading input_.

The "as a string" really refers to the fact that what is produced by
the act of reading (i.e., what is returned by the function) is a string.

But again, if the doc is not clear to you, consider letting Emacs Dev
know, by filing a bug report.  Perhaps they can improve it to remove
the perceived ambiguity.

> > Do I personally think that `SPC' should generally be self-inserting
> > during completion?  You bet I do.  And so should `?'.  And so should
> > `C-j' (newline).  (And this is the case in Icicle mode, for instance.)
> >
> > But that is not the opinion of Emacs Dev.  It took decades to finally
> > get `SPC' to be self-inserting for file-name completion (see variable
> > `minibuffer-local-filename-completion-map', in the same Elisp manual
> > node).  Patience. ;-)
> 
> Sigh. I know what you mean.

Hang in there, Oscar.