bug#56548: 29.0.50; read-expression-map conflict with read-from-minibuffer and default-value

bug#56548: 29.0.50; read-expression-map conflict with read-from-minibuffer and default-value

[Phil Sainty]

I have the following code, where the t is the READ argument,
and the DEFAULT-VALUE of "nil" means that if the user enters
no value, we read and return nil.

(read-from-minibuffer "Context expression: "
                       nil read-expression-map t
                       'read-expression-history "nil")

That worked in Emacs 27, but in Emacs 28+ we now get a temporary
message "[End of file during parsing]" alongside the prompt, and
`read-from-minibuffer' continues waiting for input, ignoring the
default value.

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=42893 is the
direct cause, as `read-expression-map' now binds RET to
`read--expression-try-read' which doesn't like the empty string.

I can stop using `read-expression-map' here; but as the purpose
of the code is to read an expression, and surely there may be
other code out there like mine, I wondered if there was a better
solution.


-Phil



In GNU Emacs 29.0.50 (build 2, x86_64-pc-linux-gnu, X toolkit, cairo 
version 1.15.10, Xaw scroll bars)
  of 2022-06-08 built on phil-lp
Repository revision: 22d3f0e95a5602b2bde763cff185f5b4fed6e53e
Repository branch: master

bug#56548: 29.0.50; read-expression-map conflict with read-from-minibuffer and default-value

[Drew Adams]

> I have the following code, where the t is the READ argument,
> and the DEFAULT-VALUE of "nil" means that if the user enters
> no value, we read and return nil.
> 
> (read-from-minibuffer "Context expression: "
>                        nil read-expression-map t
>                        'read-expression-history "nil")
> 
> That worked in Emacs 27, but in Emacs 28+ we now get a temporary
> message "[End of file during parsing]" alongside the prompt, and
> `read-from-minibuffer' continues waiting for input, ignoring the
> default value.
> 
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=42893
> is the direct cause, as `read-expression-map' now binds RET to
> `read--expression-try-read' which doesn't like the empty string.
> 
> I can stop using `read-expression-map' here; but as the purpose
> of the code is to read an expression, and surely there may be
> other code out there like mine, I wondered if there was a better
> solution.

FWIW, I don't use Emacs 28 or 29, but I too have code,
in several libraries, that calls read-from-minibuffer
with read-expression-map and non-nil READ arg.

bug#56548: 29.0.50; read-expression-map conflict with read-from-minibuffer and default-value

[Lars Ingebrigtsen]

Phil Sainty <psainty@orcon.net.nz> writes:

> (read-from-minibuffer "Context expression: "
>                       nil read-expression-map t
>                       'read-expression-history "nil")
>
> That worked in Emacs 27, but in Emacs 28+ we now get a temporary
> message "[End of file during parsing]" alongside the prompt, and
> `read-from-minibuffer' continues waiting for input, ignoring the
> default value.

I've now restored how this used to work in Emacs 29 (by introducing an
intermediary map used by `read--expression'.)

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#56548: 29.0.50; read-expression-map conflict with read-from-minibuffer and default-value

[Phil Sainty]

On 2022-07-15 05:59, Lars Ingebrigtsen wrote:
> I've now restored how this used to work in Emacs 29

Thanks Lars, that works nicely.