Possible to shallowcopy a HashMap

[longbinlai]

Thank you for this work. We are recently in using evmap in our DB system as the caching module, but we find out a case that need to use a HashMap as the Value. However, according to the trait bound, the HashMap needs to be ShallowCopiable, which is not yet implemented in the codebase. Is it possible to make it so? Thank you.

[jonhoo]

Huh, that is an interesting question... I'm guessing you mean ReadHandle specifically? Since ReadHandle isn't Sync, I doubt you'd be able to use it much even if it implemented ShallowCopy.

Or are you referring to the standard library HashMap? For that one, I think we probably could implement ShallowCopy, although it'll probably be a little involved since it has a more complex inner structure. It should "just work" if you have a Box<HashMap> instead though?