Re: fontsets/charsets documentation suggestion

[Eric Abrahamsen <girzel@gmail.com>]

On Jul 4, 2009, at 1:07 AM, Eli Zaretskii wrote:

>> Cc: emacs-devel@gnu.org
>> From: Eric Abrahamsen <girzel@gmail.com>
>> Date: Fri, 3 Jul 2009 18:40:56 -0700
>>
>>> This is in the manual, see the node "Character Sets" and maybe the
>>> other nodes from its parent "Non-ASCII Characters", if you need more
>>> background.
>>>
>>> If something is missing or unclear, please post more specific  
>>> gripes.
>>
>> Hmm, I wonder if this is part of the problem. Section 26 of my Emacs
>> Info file is 'International Character Set Support', and everything
>> relevant seems to be under this heading. I don't see a 'Character
>> Sets' or a 'Non-ASCII Characters' node. There's no index entry for
>> 'registry', neither does a grep of the info files for 'registry'
>> produce any definition of the word as related to fonts. Am I looking
>> in the wrong place? (I'm using a CVS build on Mac OSX, the ns
>> Emacs.app version.)
>
> I meant the Emacs Lisp manual, not the User manual.  Sorry, I should
> have made that clear, but for some reason (perhaps because you
> mentioned create-fontset-from-fontset-spec) I thought you were already
> looking there, and that you need this information for writing Lisp
> code.

Good lord yes, that makes much more sense. I'm approaching this purely  
as a user trying to define a multi-lingual environment, not an Elisp  
coder, and some of the Elisp manual stuff is necessary to make that  
work.

>
>> The existing examples would be clear if I'd gone into it actually
>> understanding the difference between a charset, a script and a
>> registry, and knowing which variables contained the possible values
>> for each of these three concepts. My particular use-case was defining
>> specific fonts for English/Latin, Chinese and Thai, and I did not
>> understand where 'han' came from, and its relationship to 'chinese-
>> gb2312' (I have since been directed to charset-script-alist). If I'm
>> actually missing a chunk of the documentation this would be better.
>>
>> There aren't any examples of using create-fontset-from-fontset-spec,
>> and it would be nice to see one or two. The documentation for the
>> function is technically correct, I'm sure, but is the kind of
>> documentation that's only useful if you already understand how it
>> works. Neither 26.15 Defining Fontsets nor the documentation say how
>> you actually employ a fontset once you've made it. This has got to be
>> one of the most complex areas of Emacs customization, and it would be
>> nice to err on the side of too much hand-holding.
>
> I agree that the description of fontsets in the User manual is barely
> minimal, especially if the user (a) needs to create complex fontsets
> dealing with several different character sets, and (b) does not
> already know quite a lot about character sets.  The problem is that
> most people who work on the manual know very little about subtleties
> and intricacies of fontsets, and it clearly shows in the quality of
> that section.
>
> I wonder if the stuff in the ELisp manual helps in any way.  If it
> does, we could copy some of it, with suitable editing, into the User
> manual.

I think that's exactly what should be done. Emacs 23 is far better at  
providing multilingual support, which means more and more users are  
going to want to do it, and they're going to need more help.

So maybe a step-by-step tutorial with the following:

1. A really quick version of 33.1 Text Representations
2. How to find what fonts are on your machine and available to Emacs  
(with system-dependent variations).
3. The difference between charset, registry and script, and the  
relevant functions and variables.
4. How to read a font string.
5. What a fontset is, and what it looks like in its various guises.
6. How to find currently defined fontsets (ie list-fontsets), and how  
they relate to each other (I've got fontset-default, fontset-standard,  
and fontset-startup and I have no idea which of those I should be  
working with).
7. How to use set-fontset-font and create-fontset-from-fontset-spec to  
create and modify fontsets. Describe the argument variations within  
the manual, not just in the function docs.
8. How to examine existing characters in buffers (ie C-u C-x =), and  
to use that information to inform your usage of the above two functions.

I'd be happy to assist in whatever way possible – I could suggest more  
additions to the manual or read through new docs (I'm an editor, among  
other things). I know squat about fontsets, obviously, but maybe that  
could be useful.

Thanks for your responses on this!

Eric