Use custom cookiecutter as library in custom CLI tool

[apirogov]

There are many desired configurations for the template, such as

• Github vs Gitlab
• include or exclude certain parts
• example code (which kind?)
• different "modifications"

Creating forks of this repository seems to be a recipe for maintainability nightmare, while working with the tricks possible in a "plain" cookiecutter repo is reaching its limits (too much conditional rendering turns it into a mess).

The solution is to use cookiecutter as a library and add some custom wrapping code for orchestrating it. Most users probably won't have cookiecutter on their system, so it does not matter much if they need to pip install cookiecutter, or a custom CLI tool of this repository. The upside would be much more flexibility and potential for customizing the template for each user.

This would simplify taking care of certain differences between Github and Gitlab (i.e. help with #15).

[apirogov]

Template Config

• All settings and presets should be loaded from .cookiecutterrc, if available
• We can use a custom section in the config, e.g. a fair-python-cookiecutter section
• The config can be managed using pydantic + pydantic_yaml (with extra = allow on top level)

Functionality

• Input: The tool should prompt for variables not defined/overridden in the config
• Pre-processing: from the results, it should
  • generate a temporary cookiecutter template directory
  • add/remove/modify files according to enabled features etc.
  • generate required extra context / update cookiecutter.json
• Generation: Next, cookiecutter is used to render the adjusted template
• Post-processing:
  • run the script to lock the dependencies, create the first commit, etc.
  • clean up temporary files etc. (use platformdirs instead of tempfile to get a suitable location!)

Streamlining

In the course of implementing this, also it should be reconsidered how:

• duplication between the template vs the tool itself is avoided (currently it is a mix of symlinks and copypaste)
• how the template can be developed further more easily (e.g. currently updating deps/lockfiles is painful)