Include tag

[japsu]

TODO:

• [x] Correctly detect JSON templates being included (hoist use of determine_format up from emrichen.__main__ to Template.parse?)
• [x] Fix !Defaults over !Include
• [x] Fix consecutive imports messing up the current path (FileNotFoundError: [Errno 2] No such file or directory: 'subdir/subdir/foo.in.yml' on !Include subdir/foo.in.yml after !Include subdir/bar.in.yml on top level)

Further improvement:

• What shall we do with the drunken sail… err, I mean, multiple documents?
  • Does it make sense to include multi-document templates?
  • Could this be allowed as a special case when !Include happens at the top level of the root template?
• Include multiple files by glob?
  • Where does this make sense? At the top level (spawn multiple documents)? I'd like to do something like !Include resources/*.in.yml in a Kubernetes template, with each includee hosting one (or more?) CRDs.
  • Should this be another tag altogether?

[akx]

Does it make sense to include multi-document templates?

I think

!Include
  path: ./foo.xyx
  multi: true

or

!MultiInclude ./foo.xyx

makes sense. It could expand into multiple top-level documents where supported (YAML output) or a plain list where not.

Include multiple files by glob?

Definitely makes sense. Makes it easy to do ./conf.d style things too (with the hopefully obvious requirement that the tag sorts the list of filenames before including them).

(Actually, for better composability, maybe just a !Glob tag and !Include accepting a list of filenames?)