>>> For `defcustom' autoload generates no more than
>>>
>>> (defvar org-capture-templates nil "...")
>>>
>>> It seems, behavior depends on whether `org-capture-templates' has the :set
>>> attribute.
>> Not really, all defcustoms have a :set attribute, be it passed
>> explicitly as a parameter or the default value, set-default. This issue
>> happens with all autoload functions that use a custom variable: if they
>> are called inside a let form binding that variable and the feature was
>> not loaded yet, the let-binding will have no effect.
>
> To avoid misunderstanding. I was testing with Emacs-26.3 (Ubuntu-20.04
> focal LTS system package) and did not explicitly set lexical binding
> cookie in an .el file. However defcustom autoloading was assumed.
>
> ;; simulate effect of ;;;###autoload
> (defvar org-capture-templates nil)
>
> (defun print-org-capture-templates ()
> (message "print-org-capture-templates")
> (pp org-capture-templates)
> (message "-----"))
> (let ((org-capture-templates
> '(("d" "default" entry
> (file "/tmp/capture-test.org")
> "* %?"))))
> (print-org-capture-templates)
> (require 'org-capture)
> (print-org-capture-templates))
>
> Second call of print-org-capture templates prints nil with original
> definition of `org-capture-templates' but it prints locally let-bound
> value if I comment out the :set attribute.
>
> I am not disputing any observation from your thorough study
> mid:paxpr06mb7760a3031924ba897fd082e4c6...@paxpr06mb7760.eurprd06.prod.outlook.com
> (it seems message delivery took several hours, so I noticed it after I
> sent my message).
Yes, I was wrong about that. Instead of testing it without :set
argument, I had tested it with a :set argument that was just
set-default plus some messages for debugging. I assumed that it was
equivalent since the documentation says that set-default is the default
value for :set. However it turns out that the actual default value that
is used when no argument is passed is set-default-toplevel-value. With
the later it works (with dynamic binding or autoload variable), but with
the former it doesn't. I think I tested once without :set argument, but
I must have used lexical binding so it didn't work anyway, so I
concluded that it didn't work either in that case.
