bug#38427: 26.2; skeleton-insert does not set str consistently

bug#38427: 26.2; skeleton-insert does not set str consistently

[Tim Landscheidt]

Given (A):

| (let
|     ((somevalues '(("a" . "123") ("b" . "456"))))
|   (skeleton-insert
|    '("Prompt: "
|      (cdr (assoc str somevalues)) | str ?\n)))

Emacs asks for input with "Prompt: " and with "a" given, it
outputs "a" instead of the expected "123".

However, with (B):

| (let
|     ((somevalues '(("a" . "123") ("b" . "456"))))
|   (skeleton-insert
|    '("Prompt: "
|      str ?\n
|      (cdr (assoc str somevalues)) | str ?\n)))

and input "a", it outputs "a" and then "123".

This appears to be due to str being set on the first use on
its own and being:

| (setq str (skeleton-read (quote "Prompt: ") nil nil))

before that (which is not a key in somevalues).

This is probably best shown by (C):

| (let
|     ((somevalues '(("a" . "123") ("b" . "456"))))
|   (skeleton-insert
|    '("Prompt: "
|      (cdr (assoc str somevalues)) | "nothing" ?\n)))

which immediately outputs "nothing", without prompting the
user.

This might be a case of PEBKAC, but to me it feels "unnatu-
ral" that removing "str ?\n" from (B) to (A) does not only
remove the line from the output, but changes the meaning of
the skeleton altogether.

(In my use case, I could work around that by outputting str
in a comment, and in general one could probable just add
some dummy like "str (delete-backward-char (length str))",
but this feels very hackish and brittle.)

bug#38427: 26.2; skeleton-insert does not set str consistently

[Lars Ingebrigtsen]

Tim Landscheidt <tim@tim-landscheidt.de> writes:

> Given (A):
>
> | (let
> |     ((somevalues '(("a" . "123") ("b" . "456"))))
> |   (skeleton-insert
> |    '("Prompt: "
> |      (cdr (assoc str somevalues)) | str ?\n)))
>
> Emacs asks for input with "Prompt: " and with "a" given, it
> outputs "a" instead of the expected "123".

Evaluating that form gives me:

Debugger entered--Lisp error: (void-variable somevalues)
  (assoc str somevalues)
  (cdr (assoc str somevalues))
  eval((cdr (assoc str somevalues)))
  skeleton-internal-1((cdr (assoc str somevalues)) nil nil)

I'm not at all familiar with how skeleton works, but a test case that
works would help when trying to debug.  :-)

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

bug#38427: 26.2; skeleton-insert does not set str consistently

[Jean Louis]

* Lars Ingebrigtsen <larsi@gnus.org> [2020-11-01 17:48]:
> Tim Landscheidt <tim@tim-landscheidt.de> writes:
> 
> > Given (A):
> >
> > | (let
> > |     ((somevalues '(("a" . "123") ("b" . "456"))))
> > |   (skeleton-insert
> > |    '("Prompt: "
> > |      (cdr (assoc str somevalues)) | str ?\n)))
> >
> > Emacs asks for input with "Prompt: " and with "a" given, it
> > outputs "a" instead of the expected "123".
> 
> Evaluating that form gives me:
> 
> Debugger entered--Lisp error: (void-variable somevalues)
>   (assoc str somevalues)
>   (cdr (assoc str somevalues))
>   eval((cdr (assoc str somevalues)))
>   skeleton-internal-1((cdr (assoc str somevalues)) nil nil)
> 
> I'm not at all familiar with how skeleton works, but a test case that
> works would help when trying to debug.  :-)

I am using skeletong often. And I was of opinion it was made to create
M-x interactive functions as skeletons to quickly insert such snippets
or interactive templates:

(define-skeleton dear-friend
  "Start a letter"
  nil
  "Dear " (setq name (skeleton-read "Name: ")) ", 

Thank you for your feedback.

" _ "

Greetings,
Joe
")

This gives me M-x dear-friend

If there is region marked the _ will replace it with region. It is
very handy.

Tim, I suggest that you define skeleton that works by
`define-skeleton' and then try using it in a function. On the other
hand using skeletons in function somehow beats their purpose.

(let ((somevalues '(("a" . "123") ("b" . "456"))))
(skeleton-insert
 '(nil (setq str (skeleton-read "Var: "))
 (cdr (assoc str somevalues)) | str ?\n)))

Does that work?

I have no idea what | means here.

bug#38427: 26.2; skeleton-insert does not set str consistently

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Evaluating that form gives me:
>
> Debugger entered--Lisp error: (void-variable somevalues)
>   (assoc str somevalues)
>   (cdr (assoc str somevalues))
>   eval((cdr (assoc str somevalues)))
>   skeleton-internal-1((cdr (assoc str somevalues)) nil nil)
>
> I'm not at all familiar with how skeleton works, but a test case that
> works would help when trying to debug.  :-)

More information was requested, but no response was given within a 
month, so I'm closing this bug report.  If progress can be made,
please respond to this email and we'll reopen the bug report.

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