Don't always derefence ref

how_to/Change_34.md

@@ -0,0 +1,15 @@
+- data: Don't always dereference refs (for `ugit k`)
+
+Actually, it's not always desirable to dereference a ref all the way. Sometimes
+we would like to know at which ref a symbolic ref points, rather than the final
+OID. Or we would like to update a ref directly, rather then updating the last
+ref in the chain.
+
+One such usecase is `ugit k`. When visualizing refs it would be nice to see
+which ref points to which ref. We will see another usecase soon.
+
+To accomodate this, we will add a `deref` option to `get_ref`, `iter_refs` and
+`update_ref`. If they will be called with `deref=False`, they will work on the
+raw value of a ref and not dereference any symbolic refs.
+
+Then we will update `k` to use `deref=False`.

ugit/base.py

@@ -161,7 +161,7 @@ def get_oid(name):
         f"refs/heads/{name}",
     ]
     for ref in refs_to_try:
-        if data.get_ref(ref).value:
+        if data.get_ref(ref, deref=False).value:
             return data.get_ref(ref).value
 
     # Name is SHA1

ugit/cli.py

@@ -121,10 +121,11 @@ def k(args):
     dot = "digraph commits {\n"
 
     oids = set()
-    for refname, ref in data.iter_refs():
+    for refname, ref in data.iter_refs(deref=False):
         dot += f"'{refname}' [shape=note]\n"
         dot += f"'{refname}' -> '{ref.value}'\n"
-        oids.add(ref.value)
+        if not ref.symbolic:
+            oids.add(ref.value)
 
     for oid in base.iter_commits_and_parents(oids):
         commit = base.get_commit(oid)

ugit/data.py

@@ -16,9 +16,9 @@ def init():
 RefValue = namedtuple("RefValue", ["symbolic", "value"])
 
 
-def update_ref(ref, value):
+def update_ref(ref, value, deref=True):
     assert not value.symbolic
-    ref = _get_ref_internal(ref)[0]
+    ref = _get_ref_internal(ref, deref)[0]
     ref_path = f"{GIT_DIR}/{ref}"
     Path.mkdir(ref_path, exist_ok=True)
     with open(ref_path, "w") as f: