[Texmacs-dev] Questioning the concept of document styles

[Norbert Nemec]

Hi there,

I spent some time thinking why working with document styles in TeXmacs feels 
so clumsy. My result was, that the very concept of document styles, that 
TeXmacs copies from LaTeX, has to be questioned. Obviously, I can't avoid 
touching some fundamental questions here, so I'll take care to be as clear as 
possible in writing the following.

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Document styles vs. templates

Almost all modern word processors and other document-editing programs use a 
system of "templates" for creating new documents of different standard types 
(letter, article, book, whatever).

The usage of a template differs fundamentally from that of a style: the 
template is used only at creation time. The contents are simply copied to the 
new file. Afterwards, the default settings given in the template can be 
edited directly in the file. Editing the template will only affect future 
works. A template basically is just a plain file, so any user can edit and 
create templates just the same way he does with his documents.

Document styles however are not copied but referenced in documents. Editing a 
style file will affect all existing documents that use it. To change defaults 
given in a style, you can't just edit them in some place, but you have to 
override them in the document.

Theoretically, a style is not different from a plain document.
Practically, you have to think hard what to put into a style, since changing 
it afterwards is a real pain.

Theoretically, you can change the style of an existing document.
Practically, it won't work because the document uses markup that might not 
even exist in the new style. (Just change a "book"-style document to style 
"article" and you'll see...)

Theoretically, the style concept should ensure consistency in the look of 
documents.
Practically, you don't even want that consistency: Why would you want an 
article you wrote three years ago (using your personal style file) to look 
similar to newer articles? Currently, you would actually have to archive old 
documents along with their style files to ensure they still work lateron 
without being completely distorted just because you changed your personal 
preferences and edited your personal style file?

Theoretically, the different elements of the predefined styles (sectioning, 
header/footer, environments, etc.) should be modular and freely combinable.
Practically, disecting a style is almost impossible because of 
interdependencies. Cleaning up the package/style system delivered with 
TeXmacs also is about impossible, because it would break oodles of existing 
documents.

Theoretically, it should be possible to override detailed settings of a style 
used.
Practically, you really have to know the internals of the style. (Just try to 
use "article" style and then change the look of the footer...) Also, there is 
no clear interface for overriding settings of a style, resulting in the fact 
that the existing package/style system can't be maintained at all without 
breaking compatibility...

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That being said, I believe that the design decision in LaTeX definitely was a 
big error. The concept of documents styles really is obsoleted by the modern 
concept of templates.

Once, styles were meant as a means of separating formatting from content. 
Anyway, what we really would need is to separate those *within* a document. 
Every document should be thought of as a combination of content and 
formatting. Keeping the formatting outside the document in a centralized 
style file might help in those cases where several documents are being worked 
on in parallel and their style should stay synchronized. (Like, e.g. a 
web-site using CSS) for everyday use, though, people use TeXmacs to work on 
one document at a time and the individual documents only have to be 
consistent within themselves.

If people want their documents to look similar, they can just extract the 
formatting section from one and put it in a template for future documents. If 
they want the formatting of a collection of documents to stay synchronized, 
that should be done by some "include" mechanism.

I have no idea about a smooth transition plan. My proposal for how it should 
be, though:
* rework the current "packages" into something really generic, containing 
mechanisms, but not decisions about details (i.e. one file "sectioning" that 
works for all kinds of documents with a clean interface how the individual 
document types can configure it to their needs)
* the details of different packages should be configurable independantly: one 
should be able to change the look of the footer independant of the sectioning 
scheme that is configured for the document.
* write templates: e.g. book, article, seminar, whatever -- a template file 
should only contain *configuration* not *mechanisms*
* for every configuration option, define a clean interface to set it in a 
document in such a way, that a document can easily be split in a formatting 
and a content section.

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I know, these suggestions are extremely ambitious and I have no idea, how far 
you might agree and whether anybody thinks it worthy to even discuss the 
matter. Maybe, it really is too late to do such fundamental design decisions, 
but I think it is worthy to at least think about the matter.

Ciao,
Nobbi

-- 
______________________Norbert Nemec <address@hidden>

    Universität Erlangen-Nürnberg, Germany            
    Institut für Theoretische Physik III             
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