Follow-up plan regarding changes to resolvers

[odelalleau]

#445 introduces several changes to resolvers that triggered multiple discussions on related follow-up changes. Here is an overview of what is planned once #445 is merged:

• Address Overriding configuration using an environment doesn't trigger type checks when merging into Structured config #488 by validating & converting the result of all interpolations (both node interpolations and resolver outputs) when the target node is typed
• Do a pass on the notebook to make sure it is in synch with the doc, and works with Binder (Update notebook to synch with the docs #544)
• Change the env resolver so that it does not parse environment variables anymore, instead keeping them as strings (that may be cast into a different type thanks to the previous bullet point) -- will also resolve Add env_str resolver built-in resolver #383
• Add support for resolver namespaces (ex: oc.env) and deprecate the plain env resolver (Deprecation of the env resolver for variable environment interpolations #573)
• Add new resolver oc.decode to parse strings (ex: those output by the oc.env resolver) (Add an oc.decode resolver to parse and evaluate strings #574)
• Improve API of register_new_resolver() according to Improve the API of register_resolver() #370
• Deprecate get_resolver() (Deprecation of OmegaConf.get_resolver() #608)
• Forbid whitespace characters around dots in node interpolations and resolver names (Forbid whitespaces around dots in node interpolations & resolver names #594)
• Deprecate OmegaConf.is_none() (Deprecate OmegaConf.is_none() #547)
• Implement new resolver cache behavior as discussed in [Discussion] Resolver cache behavior #526
• Add support for $ in key names (see [Feature Request] Allow keys with $ in them facebookresearch/hydra#1437 (comment)) => Allow '$' character in key names in the grammar #600 (OmegaConf) / Override grammar: allow the dollar sign in key names facebookresearch/hydra#1605 (Hydra)
• Fix issue with handling of quoted strings (Quoted strings are not always properly parsed by the grammar #617)
• Add resolvers oc.dict.values and oc.dict.keys (Add new resolvers oc.dict.keys and oc.dict.values #643)
• Add resolver oc.create (Add new resolver oc.create #645)
• Use getitem syntax as per [Feature Request] Array Element Overrides from dotlist via getitem syntax  #179
• SImplify the escaping of quotes (New syntax for nested quoted values #695)
• Simplify escaping further (Grammar: only un-escape \\ in situations where escaping is required #708)
• Fix crash when escaped interpolations do not follow the expected interpolation syntax (Escaped interpolations trigger a GrammarParseError if they don't follow the expected interpolation grammar #666)
• Port corresponding changes to Hydra (Override grammar: allow question marks in unquoted strings facebookresearch/hydra#1598 / Quoted values are not valid dictionary keys anymore facebookresearch/hydra#1599 / Fix escaping in quoted values facebookresearch/hydra#1601 / Override grammar: allow the dollar sign in key names facebookresearch/hydra#1605)
• Address thread-safety concern related to parsing of interpolations (Thread-safety concern related to interpolation parsing #715)

Documentation (to be done in Q3'21):

• Document OmegaConf's grammar (when doing so, also take care of Add new resolver oc.create #677 (comment))
• [ ] Update OmegaConf's slide deck (will transfer task to someone else)
• [ ] Create a dedicated doc page for interpolations (Type validation of interpolations #578 (comment)) (will transfer task to someone else)
• Create a dedicated doc page for built-in resolvers (Add new resolvers oc.dict.keys and oc.dict.values #644 (comment)) (done as part of oc.deprecated #679)

[omry]

I am going to release 2.1 soon.
Out of the remaining list, none if blocking. The most important item is documenting the grammar.

[odelalleau]

Closing as everything is either done or will be transferred to someone else.