[Pre-RFC] DNS domains as package namespaces

Is there any reason not to be able to use an already published crate as a namespace(parent)? That way we don't need a separate naming system and in many cases this is also what you want (e.g. tokio-util could be at tokio@util [1]). In that case namespaces would be more like child-crates (possibly even allowing parent@child@subchild if desired.

This would avoid issues like "I have had my crate published for years now but now can't use the namespace with the same name to put other crates in".

Random thought I had to post (I have no idea if this would actually be a good system):

What if a crate author could simply choose a namespace, even if it is already used by someone else, then store a unique number (or a hash) in Cargo.lock [2] that clearly identifies which one should be used (set on first use and cargo warning loudly if you are adding a crate from a namespace with the same human readable name, with an escape hatch if you really want to use the other one.

Example: Given two namespaces called tokio, one with hash/unique identifier "AAAA" and the other with "BBBB":

• tokio@tracing: defaults to the first one that was published (or uses the namespace in Cargo.lock)
• tokio@tracing: {version = "*", namespace_hash = "BBBB"}: Select which one to actually use, making it possible to use them but with some friction.

1. Imports would probably stay tokio-util, not using the namespace at all. ↩︎

2. Not always committed to git, I know. ↩︎