Re: [O] [RFC] Org document concept + document property drawers

[Adam Porter]

Gustav Wikström <address@hidden> writes:

Hi Gustav,

Thanks for your reply.  I sent my most recent message, which reiterated
my question, before this message of yours came through.

>> This is a very interesting idea, and I don't want to dismiss your work,
>> but I am concerned about how much third-party code will likely break by
>> changing the results returned by org-element for parsing an Org buffer.
>> I haven't thoroughly studied all of the code in your patches, so I may
>> be wrong, but I think the breakage could be extensive.  For example,
>> simple operations like destructuring the results of org-element parsing
>> functions may be broken.  Have you done any investigation into this
>> issue?
>> 
>> Maybe there should be a transitional period in which the existing
>> org-element parsing functions would work as before, and the new
>> document-level elements would be returned by a new org-element
>> document-level parsing function.  Frankly, if there is breakage,the
>> transition would probably take a few years, because there is a lot of
>> code out there that has worked for years and may not be updated or
>> replaced for years.
>
> I have not investigated much into that to be honest. I'd argue that
> it's a fairly trivial change in terms of the parser though. Everything
> will work as before except when you're after the whole buffer
> syntax-tree. In that case one will have to dig one step deeper into
> the tree to find the content.
>
> Previous tree: 
> (org-data nil CONTENTS)
>
> With this patch:
> (org-data nil (document (doc-props) CONTENTS))
>
> Yeah.. The structure changed a bit. But it's a fairly trivial change 
> in my opinion. Everything else works as before AFAIK... But I might be 
> overseeing something. Please enlighten me in that case!

Thanks, that's a helpful illustration of the difference.

I'm glad that it only changes the result of parsing entire buffers.
That will limit the breakage.

However, there is code in the wild that does parse entire buffers that
way.  So that will break some code.  At least the necessary changes
would be minor.

However, if it does indeed precipitate a major Org version increment,
then such code will likely need to maintain compatibility with
older code for some time, because, like Emacs, Org versions tend to
stick around for a while.

Another question: how does this patch affect org-export backends?  I've
only a passing familiarity with them.  I'm guessing that some may break,
some of which may live outside of the Org repo.  It might be a good idea
to take a look at some of the ones on MELPA to see if they would be
affected.