bug#19217: 25.0.50; `C-M-x' (`eval-defun') on a `defface' that is not top-level

[Drew Adams]

Hi Alan,

> Starting from emacs -Q, it works, for both face & var.  With my
> setup, however, it does not work (no change from before).  Dunno
> why.  Tried it with `lexical-binding' t and nil - neither worked.
> 
> I'll bisect my setup when I get a moment, to try to find out why it
> doesn't work for me.
> 
> Thanks for working on this.

I found the explanation.  I bind `C-x C-e' to `pp-eval-last-sexp',
not to `eval-last-sexp'.  Apparently the latter got considerably
redefined after Emacs 24.4, so that `pp-eval-last-sexp' is no
longer parallel with `eval-last-sexp' - the code is very different.

Your fix seems good for `eval-last-sexp'.  But I would like to
also see a similar fix for `pp-eval-last-sexp'.  Could you
perhaps take a look at fixing that as well?

I filed a separate bug (#19362) for bringing `pp.el' into line
with the changes that were made in moving from `lisp-mode.el'
to `elisp-mode.el'.  I'm not sure about all that might be
involved for such a fix, as I don't know just what has changed.
So that bug report is worded vaguely.

But I would at least like to see `pp-eval-last-sexp' updated
similarly to how `eval-last-sexp' was (for Emacs-Lisp buffers).
A quick glance suggests that the change involves respecting
`lexical-binding', but it might be more or other than that.

Could you perhaps take a look?  I would like to be able to
get both (a) any advantages brought to `eval-last-sexp' by
the Emacs 25 changes to it and (b) the advantage of your
fix to it (this bug).  But I also want to be able to continue
using `pp-eval-last-sexp' instead of `eval-last-sexp'.
I just want the former to enjoy the same advantages as latter.

I have my own enhancement to `pp-eval-expression' (which is
used by `pp-eval-last-sexp'), but the changes I make to that
are probably orthogonal and I will be able to make them to
whatever updated definition of `pp-eval-last-sexp' there is.

---

FYI, the changes I make to `pp-eval-expression' are these:

1. Read with completion using `pp-read-expression-map'.
2. Progress message added.
3. Added optional arg and insertion behavior.
4. Respect `pp-eval-expression-print-length',
   `pp-eval-expression-print-level', and
   `eval-expression-debug-on-error'.

#1 means bindings for `lisp-indent-line', `lisp-complete-symbol',
   `indent-sexp', `eval-defun', and `indent-pp-sexp'.

#3 means this:
With a prefix arg, insert the value into the current buffer at point.
 With a negative prefix arg, if the value is a string then insert it
 into the buffer without double-quotes (`"').

#4 means you can use different values from the same
options without the prefix `pp-'.

---

FYI, I do this, wrt keys:
(substitute-key-definition 'eval-last-sexp
                           'pp-eval-last-sexp global-map)
(substitute-key-definition 'eval-expression
                           'pp-eval-expression global-map))