Re: How to add to header-includes?

[Oliver <news-WPTjrydoUPgeaOpM6FAJmQkbCANdLtlA@public.gmane.org>]

Thanks Albert

I will try it out.

Cool that you can do something like that in a filter! I had thought filters can only change the AST - or is the metadata part of the AST?

Happy pandocing,
Olli

On 23 May 2023, at 0:27, Albert Krewinkel wrote:

> oliver <news-WPTjrydoUPgeaOpM6FAJmQkbCANdLtlA@public.gmane.org> writes:
>
>> When I use header-includes: in a metadata-file I can not add more
>> header lines to it, neither via document YAML nor via -H <file> on
>> the command line. The previous includes are always forgotten.
>>
>> How can I add header stuff from a file and in the documents YAML?
>
> Bit crude, but here's a Lua filter that can help with this. The
> `--include-in-header`/`-H` option must be replaced with `-M
> include-in-header=...`, and the default includes must be specified in
> the `default-includes` field.
>
>
> ``` lua
> -- file: includes.lua
> local function ensure_list (x)
>   return pandoc.utils.type(x) == 'List' and x or pandoc.List{x}
> end
>
> local function read_file (filename)
>   return pandoc.RawBlock(FORMAT, io.open(filename, 'rb'):read('a'))
> end
>
> function Meta (meta)
>   -- Add to header-includes
>   meta['header-includes'] = ensure_list(meta['header-includes'])
>   meta['header-includes']:extend(ensure_list(meta['default-includes']))
>   meta['header-includes']:insert(read_file(meta['include-in-header']))
>
>   -- unset custom include fields
>   meta['extra-includes'] = nil
>   meta['default-in-header'] = nil
>
>   return meta
> end
> ```
>
> -- 
> Albert Krewinkel
> GPG: 8eed e3e2 e8c5 6f18 81fe  e836 388d c0b2 1f63 1124
>
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