WIP: Global config

[ftes]

Summary:

• Add Dx.Repo, similar to Ecto.Repo
• that acts as a decorator for all Dx functions
• and applies default options in this precedence: Dx.fn(..., opts) > default_options() > Mix.Config > use.

[ftes]

@arnodirlam Lets discuss before adding tests.

[arnodirlam]

Thanks a lot for the PR and the work you put in here. I'll have to think about this for a bit and also do some research on other approaches, and will get back to you here 🙏

To get started, why did you choose this approach, and did you consider any other approaches? @ftes

[ftes]

Sure, this one's not urgent so definitely worth it to take your time.

Tbh I jumped onto the Ecto.Repo approach after only short consideration, because I know it, I find it useful and somewhat similar to this case.

What I considered:

• Support Mix.Config for environment-dependent default options (e.g. timeout)
• Support Ecto.Repo style decorator module
  • allows defining multiple "repos" to support use-case specific default options
  • support both static (use opts) and dynamic default_opts/1 default opts
  • ease of adoption: copy well-known ecto approach

Things it might be worth to consider:

• unnecessary complexity: is this overkill?
• naming: is Dx.Repo a good name?