Re: [PATCH v2 00/10] Use a structure for object IDs.

>Michael Haggerty <mhagger@alum.mit.edu> writes:
>> 4. We continue to support working with SHA-1s declared to be (unsigned
>> char *) in some performance-critical code, even as we migrate most other
>> code to using SHA-1s embedded within a (struct object_id). This will
>> cost some duplication of code. To accept this approach, we would need an
>> idea of *how much* code duplication would be needed. E.g., how many
>> functions will need both (unsigned char *) versions and (struct
>> object_id *) versions?
>
>Ideally, only the ones that knows the underlying hash function is
>SHA-1 (i.e. anybody who mentions git_SHA_CTX), moves bytes from/to
>in-core object name field and raw range of bytes (e.g. sha1hash());
>everybody else like hashcpy() and hashcmp() should be able to do its
>thing only on structs and a generic-looking constant that denotes
>how many bytes there are in the hash (or even sizeof(struct oid)).
>
>I do not know what kind of code duplication you are worried about,
>though.  If a callee needs "unsigned char *", the caller that has a
>"struct object_id *o" should pass o->hash to the callee.