RE: C-x C-e with prefix arg

[Drew Adams]

> > 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.
> 
> Isn't truncated output intended mostly for beginners
> to not overwhelm them with long output?  If yes,
> then it should be used by default.

For me, truncated output is useful for anyone who wants to see the overall
picture and doesn't need the exact value.

That is especially important for printing to the echo area.

To me, it does not make sense as the default behavior for printing the value
into the current buffer.  Why?  Because, as I said at the beginning, I think
that most users do that in order to _do something_ with the value - something
that requires the full value.  Typically, I want to edit it or perhaps examine
parts of it in detail.

You don't have to be an expert to want to do such things.  By your logic, `C-h
v' should also print using elision.

When I do `C-h v bookmark-alist' I really want to see the full alist.  But maybe
another user does not.  We could imagine options governing printing there too.

My point is that wanting to see the full value is not something limited to
experts, and wanting to see only an executive overview of the value is not
something limited to novices.  A better distinction is wrt the buffer,
minibuffer or other, and we can make a reasonable guess as to the need (full or
partial view) for each kind of buffer.

I've made my suggestion wrt such guessing: when users print the value to the
current buffer, I think they usually want the full value.

> > Most of the time when you want to print the value, you want 
> > the whole value, not an abbreviation.  That's my claim.
> 
> I agree that most of the time you want the whole value.
> That's why I have in ~/.emacs ;-)
> 
>   (custom-set-variables
>    '(eval-expression-print-length nil)
>    '(eval-expression-print-level nil)
> 
> But the question is what should be the default behavior.
> It seems this feature for the elided display of long lists
> was created with the intention to be used by default.

Who knows what was behind the original design?  Maybe someone just took the
behavior that made sense for the minibuffer and continued it for the current
buffer too.  Maybe someone was too lazy to figure out another way to do things.
Maybe someone, like you apparently, felt that giving users options to configure
would give them enough control over the printing.

IMO, users should have a quick way of getting the full value in the current
buffer, _even if_ they generally prefer the partial value and have reflected
that more general preference in the user options.

If you really wanted to complicate things, you could make the option record a
preference for the minibuffer and another one for the current buffer.  But even
then, maybe a user would want to sometimes choose another behavior on the fly
(e.g., using a prefix arg).