Comment on Org Export Reference

Comment on Org Export Reference

[James Harkins]

I've been working on an export backend for personal use, and I find the 
documentation on worg to be... not quite what I need. In the spirit of 
suggesting an avenue for improvement, then:

The page covers a lot of details, but less in the way of context. For 
instance, the toolbox is documented extensively, but I didn't see a 
comprehensive list of the transcoding functions that a backend should 
implement, nor details of these functions' inputs, nor recommendations for 
handling elements that aren't obvious (tags, links, footnotes...). In my 
first attempt, I even left out ox-*-template -- I had no idea what the 
template was or its importance! (It is actually sort of covered on worg, 
but it's buried in a quoted docstring with nothing to highlight its rather 
crucial nature.)

I've had to infer these from ox-ascii.el, which also covers a lot of cases 
that aren't relevant to this exporter, making it hard to guess what is 
strictly necessary. The result for me has been rather remarkable amounts of 
wasted time.

I also wonder about documenting functions without documenting their 
arguments. Like, yesterday I was trying to use org-export-get-parent: 
first, find out that the function exists on worg, then switch to emacs and 
C-h f it to find out *really* how to use it. Why C-h f? Because the worg 
page says *nothing* about the arguments!

At the very least, another section needs to be added, listing the elements 
that need to be transcoded. Also some common cases might be nice, e.g., 
what's the canonical way to access tags? Properties? Typical cases for 
links that you wouldn't think of unless you already know what you're doing 
(but if you already knew what you're doing, you wouldn't be scouring the 
reference)?

I'll add that, despite some painful false starts, I've got a shocking 
amount of the elements working already. Some, that I might have expected to 
be hard (e.g., plain lists) were close to trivially easy! So I'd say the 
exporter design is a thing of beauty -- serious applause for this -- it's 
just that the entry point involves too much puzzling over source code and 
not enough well-organized explanation.

hjh

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Re: Comment on Org Export Reference

[Rasmus]

Hi James,

James Harkins <jamshark70@qq.com> writes:

> I've been working on an export backend for personal use, and I find
> the documentation on worg to be... not quite what I need. In the
> spirit of suggesting an avenue for improvement, then:

I'm happy you found of ox and org-element useful.  Nicolas' work is indeed
very pleasant to work with, as you found out.

It would be great if you would address the documentation issues that you
raised in form of, preferably, a patch to org.texi, or alternatively an
addition to Worg.

Thanks,
Rasmus

-- 
Tack, ni svenska vakttorn. Med plutonium tvingar vi dansken på knä!

Re: Comment on Org Export Reference

[Nicolas Goaziou]

Hello,

James Harkins <jamshark70@qq.com> writes:

> The page covers a lot of details, but less in the way of context. For
> instance, the toolbox is documented extensively, but I didn't see
> a comprehensive list of the transcoding functions that a backend
> should implement

There is no rule about what a back-end should implement (besides
template). Anyway full list of supported elements and objects, along
with all associated properties is in "Org Element API" document[fn:1].

> nor details of these functions' inputs, nor recommendations for
> handling elements that aren't obvious (tags, links, footnotes...).

I'm not sure there's a general rule to handle them. However I tried to
give real examples on how to use some tools in 

> I've had to infer these from ox-ascii.el, which also covers a lot of
> cases that aren't relevant to this exporter, making it hard to guess
> what is strictly necessary. The result for me has been rather
> remarkable amounts of wasted time.

At some point, I wanted to write a tutorial on how to create a back-end
from scratch. I even chose Markdown to do it. Unfortunately, I wrote
"ox-md.el" and, for various reasons, skipped the tutorial.

Anyway, such a tutorial is more than welcome, if you want to write one.

> I also wonder about documenting functions without documenting their
> arguments. Like, yesterday I was trying to use org-export-get-parent:
> first, find out that the function exists on worg, then switch to emacs
> and C-h f it to find out *really* how to use it. Why C-h f? Because
> the worg page says *nothing* about the arguments!

Tools section could indeed list arguments required for each tool.
However, I expect users to use Emacs internal documentation first.

Anyway, patch welcome.

> At the very least, another section needs to be added, listing the
> elements that need to be transcoded.

See above.

> Also some common cases might be nice, e.g., what's the canonical way
> to access tags? Properties? Typical cases for links that you wouldn't
> think of unless you already know what you're doing (but if you already
> knew what you're doing, you wouldn't be scouring the reference)?

There's a tool named `org-export-get-tags' with an example on how to use
it already. Likewise, there's a tool named
`org-export-get-node-property'. However, it doesn't contain an example.

> I'll add that, despite some painful false starts, I've got a shocking
> amount of the elements working already. Some, that I might have
> expected to be hard (e.g., plain lists) were close to trivially easy!
> So I'd say the exporter design is a thing of beauty -- serious
> applause for this --

Thank you.

> it's just that the entry point involves too much puzzling over source
> code and not enough well-organized explanation.

Help welcome.

Also, do not hesitate to ask questions on the ML.


Regards,

[fn:1] http://orgmode.org/worg/dev/org-element-api.html

-- 
Nicolas Goaziou

Re: Comment on Org Export Reference

[Marcin Borkowski]

On 2015-03-06, at 09:55, James Harkins <jamshark70@qq.com> wrote:

> I've been working on an export backend for personal use, and I find the 
> documentation on worg to be... not quite what I need. In the spirit of 

In fact, studying the sources for existing exporters seems to be the
best way to learn that stuff.

> suggesting an avenue for improvement, then:
>
> The page covers a lot of details, but less in the way of context. For 
> instance, the toolbox is documented extensively, but I didn't see a 
> comprehensive list of the transcoding functions that a backend should 
> implement, nor details of these functions' inputs, nor recommendations for 
> handling elements that aren't obvious (tags, links, footnotes...). In my 
> first attempt, I even left out ox-*-template -- I had no idea what the 
> template was or its importance! (It is actually sort of covered on worg, 
> but it's buried in a quoted docstring with nothing to highlight its rather 
> crucial nature.)
>
> I've had to infer these from ox-ascii.el, which also covers a lot of cases 
> that aren't relevant to this exporter, making it hard to guess what is 
> strictly necessary. The result for me has been rather remarkable amounts of 
> wasted time.

I know what you feel.  I'm about two thirds into ox-latex;-).

I don't treat it exactly like I wasted that time.  I hear that reading
other people's code is a good way to learn.  (It was also not /that/
time-consuming, either; studying ox-latex has taken me less than 5 hours
so far over the course of about three weeks (I had some breaks).  Hooray
for clocking;-)!)

> I also wonder about documenting functions without documenting their 
> arguments. Like, yesterday I was trying to use org-export-get-parent: 
> first, find out that the function exists on worg, then switch to emacs and 
> C-h f it to find out *really* how to use it. Why C-h f? Because the worg 
> page says *nothing* about the arguments!
>
> At the very least, another section needs to be added, listing the elements 
> that need to be transcoded. Also some common cases might be nice, e.g., 
> what's the canonical way to access tags? Properties? Typical cases for 
> links that you wouldn't think of unless you already know what you're doing 
> (but if you already knew what you're doing, you wouldn't be scouring the 
> reference)?
>
> I'll add that, despite some painful false starts, I've got a shocking 
> amount of the elements working already. Some, that I might have expected to 
> be hard (e.g., plain lists) were close to trivially easy! So I'd say the 
> exporter design is a thing of beauty -- serious applause for this -- it's 
> just that the entry point involves too much puzzling over source code and 
> not enough well-organized explanation.

Again, I know what you feel.  Writing a custom exporter is in fact
easier than one might think.

I'd love to see a tutorial for writing custom exporters.  (I did write
one such exporter, a modification of the HTML one:
https://github.com/mbork/org-edu-html .  I'm planning to write at least
two more.)

I might start such a tutorial, but I don't feel competent enough to make
it comprehensive.  Also, I'm not sure whether I'll be able to handle
this spare-time-wise.  But I'll think about it and I'll try to try that
(no mistake here).

What I find especially missing is: documenting the underlying data
structures (and overall architecture – in fact, I was thinking today
about writing a blog post about the main entry points to the exporter,
but this will probably have to wait a week or two), and a way to debug
it.  While generating a data structure for an element is easy
(org-element-at-point), the `info' parameter is rather mysterious for me
(yet).  I guess I'll have to run a few exporter functions through edebug
or something...

[After a while, thinking.]

OK, to be more constructive: I think I will be able to reserve some time
for studying for and writing such a tutorial.  What form would be
reasonable?  Is a github repo with an org file a good idea?  I guess
that when (or rather `if'?) it gets in a reasonable shape, transferring
it to worg might be useful, but this might not happen to soon.

> hjh

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University

Re: Comment on Org Export Reference

[Nicolas Goaziou]

Marcin Borkowski <mbork@wmi.amu.edu.pl> writes:

> What I find especially missing is: documenting the underlying data
> structures (and overall architecture – in fact, I was thinking today
> about writing a blog post about the main entry points to the exporter,
> but this will probably have to wait a week or two), and a way to debug
> it.  While generating a data structure for an element is easy
> (org-element-at-point), the `info' parameter is rather mysterious for me
> (yet).  I guess I'll have to run a few exporter functions through edebug
> or something...

`info' contents are almost completely explained in the reference
documentation ("The Communication Channel" section). Missing properties
are those used as a cache in various functions
(e.g. :resolve-fuzzy-link-cache for `org-export-resolve-fuzzy-link').


Regards,

Re: Comment on Org Export Reference

[James Harkins]

On March 6, 2015 7:21:50 PM Nicolas Goaziou <mail@nicolasgoaziou.fr> wrote:

> James Harkins <jamshark70@qq.com> writes:
>
> > The page covers a lot of details, but less in the way of context. For
> > instance, the toolbox is documented extensively, but I didn't see
> > a comprehensive list of the transcoding functions that a backend
> > should implement
>
> There is no rule about what a back-end should implement (besides
> template).

Should, or could.

> Anyway full list of supported elements and objects, along
> with all associated properties is in "Org Element API" document[fn:1].

Ah, OK! The connection between these and the exporter was, for whatever 
reason, not obvious to me. (I may perhaps be forgiven for this: a search of 
the export reference for "API" yielded no results.)

Maybe all the document needs is to call attention to the relationship and 
give a few examples. *That* is something I can handle. A full tutorial is 
more time than I can afford now, but might not be needed after all.

hjh

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