x/hashlock package improvements

[ruseinov]

• It would probably help to have some scenario tests for this to provide better overview
• Not a particular fan of using ctx.Value(contextKeyPreimage) as this seems to be global to the context and using iota (0) in this case. I would much rather prefer a format of extension:variable

[ethanfrey]

Let's just close this as we will delete the package in #540

[ethanfrey]

Not a particular fan of using ctx.Value(contextKeyPreimage) as this seems to be global to the context and using iota (0) in this case. I would much rather prefer a format of extension:variable

This is actually a powerful go trick to make package local keys in context that no other package can read or write. Got this some years ago.

Trick is keys in Context are interface{} which stores type info, and nothing can force a collision with a private type.

[ruseinov]

ah, I didn't really know this. Cool!