RE: C-x C-e with prefix arg

[Drew Adams]

> > And like those other options, it should be ignored except 
> > via `C--' or `M--'.
> 
> The default values should not be ignored by default.
> 
> The default values of `eval-expression-print-length' and
> `eval-expression-print-level' should be respected by all
> `eval-expression' related functions by default because
> they are _default_ values.
> 
> An additional prefix arg like `M--' could be used to
> override the default values.  Although `M-0' would make
> more sense because it will display more information
> (the full value of the list printed by `M-0 C-x C-e').

We've been through all of this before, I believe.

1. We've already spoken about `M-- and `C--' vs `M-0'.  The former (which was
your proposed restriction of my initial proposal of any negative prefix arg) is
preferable to the latter, IMO.  We've been through the reasons.

2. The default values of those options will, by my proposal, be for use only
with `M--' and `C--' (for `eval-last-sexp'), not for use with a non-negative
prefix arg.  That is the design I proposed.

There is nothing wrong with offering options that take effect only in certain
circumstances.  Just because an option has a default value (and every option
does) does not mean that the option takes effect by default for all commands
that make might use of it.  It is fine for a given command to make use of it in
only some contexts.

IMO, it is important that `C-x C-e' with a plain `C-u' (more generally, with a
non-negative prefix arg) ignore those options altogether and print the full
value.  That was the _point_ of my suggestion, from the beginning.  Most of the
time when you want to print the value, you want the whole value, not an
abbreviation.  That's my claim.

3. The _default_ behavior of the command, on the other hand, does not print
anything!  We are discussing only the behavior of the command when the value is
printed in the current buffer, which for `C-x C-e' means when you use a prefix
arg.