Junio C Hamano <gitster@xxxxxxxxx> writes: >> c) Replace the backpointer with a remote_state parameter. Expressive and >> fits the paradigm of "defaulting to the repo when needed", but >> interfaces are repetitive and shifts the responsibility of >> correctness to the caller (see v2). > > ... if we want to support the what-if callers, I > think the best approach would be a slight variant of c) above. > > That is, pass branch and remote_state as two parameters, and when > branch is not NULL, barf if it is not among remote_state.branches[], > to protect against nonsense combinations. Sounds reasonable to me. The resulting interface would look like the v2 one, but internally, this additional safety check will prevent misuse. >>> a) Represent detached HEAD with a non-NULL "struct branch". This will >>> let us continue using the remote_state backpointer, which makes many >>> interfaces clean, but is somewhat invasive, error-prone and it uses >>> "struct branch" for something that is not a branch, which is itself >>> an error-prone interface. >> >> I'd rather not to go there. > > Actually, I take half of that back, as I think this would be the > best direction in the longer term, and it conceptually is sound. > After all, detached HEAD is not all that special--- when we ask for > the "current branch" and the HEAD happens to be detached, we treat > it as a perfectly valid state and behave as if we are on that > unnamed branch. The state probably deserves to be represented as a > "struct branch" instance. > [...] when things have stabilized, we should revisit > and see if it is feasible to represent a detached HEAD state with an > instance of "struct branch" and how simpler the interface would become > when we did so. This "longer term direction" sounds like what I envisioned with (e). I agree that detached HEAD is a state that should be expressed with more than just NULL, though I'm not sure that "struct branch" is the correct abstraction. No point bikeshedding now of course, we'll cross that bridge when we get there ;)
