Re: [RFC] git-pack-refs --prune

Linus Torvalds [off-list ref] writes:

On Thu, 21 Sep 2006, Junio C Hamano wrote:

quoted

Ok, so I did these and the result is a 4-patch series.

Looks good to me. I would have combined 2/3, since the bulk of them is the 
calling conversion change, and they both add a new argument to the same 
function, so combining them would make just one patch that isn't even 
noticeably larger than either of the two originals, but that's just a 
small nitpick.

Actually I did these two as a single change and then later split
them.  Unfortunately cherry-picking only 3 without 2 would not
have worked anyway in this particular case with git, but an
ideal SCM would have done a better job.  It's just taste and
principle and splitting them into two would not have any
practical advantage in the real world.

Side note to interested bystanders.

Patch 2 changes function signature of for_each_ref() and
friends and adds one parameter, void *cbdata, to them and the
called-back functions.  Typical changes looked like these:

+typedef int each_ref_fn(const char *refname, const unsigned char *sha1, void *cb_data);
-static int name_ref(const char *path, const unsigned char *sha1)
+static int name_ref(const char *path, const unsigned char *sha1, void *cb_data)
-	for_each_ref(name_ref);
+	for_each_ref(name_ref, &tags_only);

Then patch 3 adds another parameter, int flags, to the same functions involved:

-typedef int each_ref_fn(const char *refname, const unsigned char *sha1, void *cb_data);
+#define REF_ISSYMREF 01
+#define REF_ISPACKED 02
+typedef int each_ref_fn(const char *refname, const unsigned char *sha1, int flags, void *cb_data);
-static int name_ref(const char *path, const unsigned char *sha1, void *cb_data)
+static int name_ref(const char *path, const unsigned char *sha1, int flags, void *cb_data)

An ideal SCM should help the user who wants to cherry pick patch
3 without patch 2, effectively applying a patch like this:

* Type definition of for_each_ref() callback function (with
  flags but without callback data):

+#define REF_ISSYMREF 01
+#define REF_ISPACKED 02
+typedef int each_ref_fn(const char *refname, const unsigned char *sha1, int flags);

* An actual callback function:

-static int name_ref(const char *path, const unsigned char *sha1)
+static int name_ref(const char *path, const unsigned char *sha1, int flags)

* The call-site of for_each_ref (note patch2 and patch2+patch3
  have the same effect):

-	for_each_ref(name_ref);
+	for_each_ref(name_ref, &tags_only);