Re: yank-media: allow users to limit image types that can be inserted

[Visuwesh <visuweshm@gmail.com>]

[ஞாயிறு அக்டோபர் 27, 2024] Eli Zaretskii wrote:

>> From: Visuwesh <visuweshm@gmail.com>
>> Cc: yantar92@posteo.net,  pinmacs@cas.cat,  rpluim@gmail.com,
>>   emacs-devel@gnu.org
>> Date: Sun, 27 Oct 2024 20:32:21 +0530
>> 
>> [ஞாயிறு அக்டோபர் 27, 2024] Eli Zaretskii wrote:
>> 
>> >> > Examine the available TARGETS, then bind
>> >> > yank-media--registered-handlers to the appropriate value when invoking
>> >> > yank-media.
>> >> 
>> >> Would that not defeat the point of yank-media, which is to present a
>> >> simple, common interface to the clipboard data to major-mode authors?
>> >
>> > Which part of the above would "defeat the point of yank-media", and
>> > why?
>> 
>> yank-media presents a uniform interface to clipboard data across
>> platforms, in principle.  This implies that there is no need to know the
>> ugly details of how the clipboard data is to be fetched, which data
>> types are available and which of them are bogus, etc.
>
> My suggestion does not require any need to know those ugly details.
> It just suggests to remove from the list the handlers a mode doesn't
> want.  Removing the, say, image/png handler from the list does not
> require any knowledge how that handler accesses the clipboard nor how
> it extracts PNG images from the clipboard.  It just requires to know
> the (trivial) fact that an image/png handler can interpret the
> clipboard data as a PNG image.
>
> So I don't think I understand your reasoning.  What did I miss?
>
>> The major-mode authors would simply write handlers for all relevant
>> data types and leave it to the user to choose the preferred type if
>> more than one of them is handled by the major-mode.
>
> AFAIU, we were talking about situations where the major mode "knows
> better" than the user, and doesn't want to leave the choice to users.
>
>> But if the major-mode authors have to cater to the user's preferred data
>> types by looking at TARGETS in their "major-mode-yank-media" command,
>> that defeats the abstraction yank-media provides...
>
> I don't understand how.  TARGETS include stuff like image/png and
> text/html; how does looking at that defeat any abstractions, and what
> abstractions are those?  We cannot consider TARGETS to be an opaque
> object anyway because then we won't be able to ask the user which of
> the MIME types she wants to yank, nor apply any advance preferences of
> the user.
>
>> The entire point of using the library, IMHO, is to leave out this
>> nasty business of handling the clipboard to a third party.
>
> What do you mean by "handling the clipboard"?  In my mind, "handling
> the clipboard" is what the handlers do, and my suggestion doesn't
> change that, nor does it require any knowledge about their works.  It
> only requires to know that each MIME type has a handler, and removing
> that handler from the list will prevent the clipboard data from being
> interpreted as that MIME type.
>
>> > If Org has its own ideas about what's best for the users in some
>> > situations, and if the users agree with that, I don't see what is
>> > wrong with that.  The common interface presented by yank-media to
>> > major modes is there so that major modes could use it in whichever
>> > ways they think is best for their users.  So I see no problems in
>> > major modes deciding to prefer some handlers over others, not in
>> > principle.
>> 
>> We do not disagree about this at all.  What we do disagree on is the
>> means by which to achieve this.  If we could specify a filter function
>> as a variable that filters out the available data types before
>> presenting it to the user, the major-mode authors would be saved the
>> burden of writing their yank-media-like command which requires the
>> knowledge of obtaining TARGETS and potentially ignoring bogus types in
>> it.
>
> How will that filter function be any different from what I propose?
> You want to filter MIME types, I suggest filtering the handler, but
> since each handler is uniquely identified by the MIME type it handles,
> what exactly is the big difference?
>
> I feel there's some gross misunderstanding here, but what is it?

I feel the same too.  I believe it would be more productive if I
proposed a patch of what I am suggesting so that things will be more
clear.  I will try to post one as soon as time permits, and will answer
rest of the questions you've raised in your message then.