How do I write a dynamic file to disk that is retained after rendering?

[coatless]

Description

Inside a Lua filter, I would like to generate a file that can be attached on an on-demand basis. So, I'm looking to add a dynamic "configuration" file.

For example, I'd like the Lua filter to be able to write out a configuration file like:

- name: config
- property:
   - render: true 

Is there a good way to go about this currently? I think all files largely have to be "fully" present to be included with a resource call.

[cscheid]

Can you explain in a little more detail what you're trying to achieve?

[coatless]

I'm aiming to use dynamically written configuration files to get around the raw block assertion issue that arose in #5666. So, the workflow would simplify from using quarto.doc.include_text() to quarto.doc.include_file(). Moreover, we can hopefully just write the configuration files once (detect if file is present and skip) to improve the setup and maintenance process for large book projects.

[dragonstyle]

Quarto 1.4 will include function quarto.doc.add_resource and quarto.doc.add_supporting which allow you to tell Quarto about dynamically generated files, and ensure that they are copied or moved to the same relative path in the output directory...

[coatless]

I think this is referring to #5709?

From the NEWS entry:

• Add support quarto.doc.add_resource and quarto.doc.add_supporting.
  • add_resource will add a resouce file to the current render, copying that file to the same relative location in the output directory.
  • add_supporting will add a supporting file to the current render, moving that file file to the same relative location in the output directory.

My use case would likely be under the add_supporting(). So, this would mean I would use Lua's write functionality to write to the _extension directory and, then, move the file to the render directory?

[coatless]

Is there a quarto specific way of checking to see if a document exists before attempting to add the resource/support file? I'd like to avoid overwriting customizations in files if already set.

[dragonstyle]

When resource/supporting files(s) are placed after rendering, the files are moved to the output directory using the the relative path to the input file that provided the supporting / resource file(s). So I'd generally say you should write the file to wherever you'd like relative to the rendered input file (and it will be in the same position in the output directory after rendering). Does that make sense?

It looks to me like we have some internal tools for working with files in LUA that we don't currently expose in our LUA API. We could take a look at exposing those to simplify this...