[Rd] Request: tools::md5sum should accept connections and finally in-memory objects

[John Mount]

> So yes, if one wants to use all the utilities or the various algos that the digest package provides, one should install and load it. But if one can live with MD5 hashes, why not use the built-in R function? (Well, without serializing an object to a file, calling tools::md5sum, and then cleaning up the file.)

Doesn't that assume that the serialization method is deterministic? Is that a documented property of the serialization tools?