Re: Exchangeing content of variables between luacode and context

[Hans Hagen <j.hagen@xs4all.nl>]

On 11/19/2019 8:34 PM, Rudolf Bahr wrote:

> My 'actual problem' is more or less a design problem: Should in a book project
> ConTeXt be the master and Luacode the slave or vice versa? Both seems possible.

nearly always context is th emaster (it is anyway as it manages the 
process)

> The task to solve is to set a photo album with say 300 DIN A4 landscape pages.
> On every page there should be 1 to 4 columns filled with photos and texts mostly
> defined in layers.
> 
> Up to now I made all in ConTeXt manually by trying, for instance::
> - To estimate the width of layers, if neighboured layers should contain photos of
>    same height with respect to center horizontally all columns at end of page.

can be done in tex of lua

> - To complete abbreviations of long picture names; it's rather annoying doing
>    this by copy and paste with hundreds of photo names; instead I'd like to type
>    a short code and Luacode should complete it to the full name.

that can be done runtime ...

> - To estimate the shift amount of all columns together in order to horizontally
>    get them centered on the page.

can be done by tex or lua

> All of these tasks can be made best by Luacode functions. And I'd like to save
> their results in the ConTeXt program permanently. With 'tokens.setters.macro()'
> it's possible only in the same, Luacode calling ConTeXt run. In the following
> run, the macro shows its original value again and the Luacode program must be
> called again to alter it.

you can store info in the tuc file (there are examplex on the wiki and 
in the test suite) or you cam create a table, save it at the end of the 
run and load it at the start

(assuming that you cannot just recalculate the values each run, but i 
assume that you have a reason for not doing that)

> So I've to think about making Luacode the master and ConTeXt the slave. Then it'd
> be possible to embody Luacode's results permanently in the ConTeXt code. Vice versa
> a solution could be to store Luacode's results in a flattened Lua table on disc.
> But the perfect relating to their ConTeXt page remains difficult when inserting
> or deleting of pages in an ensemble of 300 pages should become necessary. Another
> much simpler solution would be the proposal above, namely, to copy the ConTeXt
> program step by step and page by page to another file and introducing the Luacode
> results simultaneously.

if each page can be recognized you can make a hash of its properties and 
store the page specific data using that hash

> In [1] there is a chapter with "stepper" commands, but I didn't understand that,
> so I can't say, whether they are suitable for this issue.

unrelated

Hans

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