On 03/09/2022 15:26, Ihor Radchenko wrote:
> Max Nikulin writes:
>> The only problems
>> is that adding entries programmatically breaks easy customization
>> interface for `org-file-apps'. Currently there is the same issue with
>> `org-link-parameters' that is a defcustom variables with entries added
>> by various org extensions.
> 
> We may alter the :type specifier in `org-file-apps' to something like
> 
> :type `(repeat
>           (choice
>             ,org-file-apps-presets
>             ...))
> 
> `org-file-apps-presets' will then contain :type specs for some common
> file types and the apps. The variable can be easily populated by
> third-party packages as well.

I mean another problem. A user adds (require 'some-package) that defines 
new link type. Later the user invokes easy customization interface to 
adjust a link unrelated to some-package. At this step
links from some-package are added to user's init file. Ideally it should 
not happen and after removing of (require 'some-package) there should be 
no link types from the package in the init file at all, including 
customization section.

 From my point of view entries added to `org-link-parameters', 
`org-file-apps', etc. by packages should not affect entries managed 
through customization.

>>        I added the example with hope to better explain the purpose of this
>>        function.
> 
> I do not think that it is needed in the `org--open-file-format-command'
> docstring. If you wish, it would be better to add examples of the
> arguments and return values of `org--open-file-format-command' instead
> of showing `org-file-apps' examples.

I have removed most parts of the example. In addition I fixed some 
issues with references in the docstring (man mailcap is not recognized 
as a link for some reason yet). I changed the function to consider 
trailing backslash as a format error.

See the following message for my new idea concerning providing 
configuration for PDF viewers. Single elisp function should be more 
robust than 6 shell commands and it is better to add code than instructions.

Max Nikulin. Re: Org mode links: Open a PDF file at a given page and 
highlight a given string. Sat, 3 Sep 2022 20:00:47 +0700. 
https://list.orgmode.org/tevj61$17d8$1@ciao.gmane.io