[help] Is it possible to create a custom hash function for some (but not all) targets?

[billdenney]

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Description

When hashing nlmixr2 objects, the digest::digest() hash differs between sessions (nlmixr2/rxode2#689 (comment)). The sha1 value does not differ, though.

So, I wonder if there is a way to create a hash manually? My first thought is to use a custom repository that would be almost identical to tar_repository_cas_local taking the stable sha1 hash of the object and then storing in the local cas directory. But, I don't actually want a CAS system. I'd prefer to set a custom hash for the objects and use the rest of the targets functionality for storing the object normally.

[wlandau]

Hash functions are too low-level to expose to users.

Recent versions of targets use secretbase::siphash13() instead of digest, but from nlmixr2/rxode2#689 (comment), it sounds like you would rather exclude some files from the hashing process. In nlmixr2targets, maybe it's possible to omit these files from tracking altogether, or return a different kind of object whose hash is more stable.