On 9 June 2018 at 00:41, Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> wrote:
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index ab641bf5a9..abf07be7b6 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -919,6 +919,12 @@ core.abbrev::
> in your repository, which hopefully is enough for
> abbreviated object names to stay unique for some time.
> The minimum length is 4.
> ++
> +This can also be set to relative values such as `+2` or `-2`, which
> +means to add or subtract N characters from the SHA-1 that Git would
> +otherwise print, this allows for producing more future-proof SHA-1s
> +for use within a given project, while adjusting the value for the
> +current approximate number of objects.
How about s/, this/. This/ to break it up a little? Also, you write "+2"
and "-2" but then "N". Unify it?
Also, I'd suggest s/SHA-1/object ID/ to be future-proof.
> diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
> index f466600972..f1114a7b8d 100644
> --- a/Documentation/diff-options.txt
> +++ b/Documentation/diff-options.txt
> @@ -384,6 +384,9 @@ endif::git-format-patch[]
> independent of the `--full-index` option above, which controls
> the diff-patch output format. Non default number of
> digits can be specified with `--abbrev=<n>`.
> ++
> +Can also be set to a relative value, see `core.abbrev` in
> +linkgit:git-diff[1].
Good. You then add this paragraph to lots of other places...
> diff --git a/config.c b/config.c
> index 12f762ad92..cd95c6bdfb 100644
> --- a/config.c
> +++ b/config.c
> @@ -1151,6 +1151,17 @@ static int git_default_core_config(const char *var, const char *value)
> return config_error_nonbool(var);
> if (!strcasecmp(value, "auto")) {
> default_abbrev = -1;
> + } else if (*value == '+' || *value == '-') {
> + int relative = git_config_int(var, value);
> + if (relative == 0)
> + die(_("bad core.abbrev value %s. "
Trailing period? Same below.
> + "relative values must be non-zero"),
> + value);
> + if (abs(relative) > GIT_SHA1_HEXSZ)
> + die(_("bad core.abbrev value %s. "
> + "impossibly out of range"),
> + value);
> + default_abbrev_relative = relative;
> } else {
> int abbrev = git_config_int(var, value);
> if (abbrev < minimum_abbrev || abbrev > 40)
> diff --git a/diff.c b/diff.c
> index e0141cfbc0..f7861b8472 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -4801,16 +4801,28 @@ int diff_opt_parse(struct diff_options *options,
> else if (!strcmp(arg, "--abbrev"))
> options->abbrev = DEFAULT_ABBREV;
> else if (skip_prefix(arg, "--abbrev=", &arg)) {
> + int v;
> char *end;
> if (!strcmp(arg, ""))
> die("--abbrev expects a value, got '%s'", arg);
> - options->abbrev = strtoul(arg, &end, 10);
> + v = strtoul(arg, &end, 10);
> if (*end)
> die("--abbrev expects a numerical value, got '%s'", arg);
> - if (options->abbrev < MINIMUM_ABBREV) {
> + if (*arg == '+' || *arg == '-') {
> + if (v == 0) {
> + die("relative abbrev must be non-zero");
> + } else if (abs(v) > the_hash_algo->hexsz) {
> + die("relative abbrev impossibly out of range");
> + } else {
> + default_abbrev_relative = v;
> + options->abbrev = DEFAULT_ABBREV;
> + }
> + } else if (v < MINIMUM_ABBREV) {
> options->abbrev = MINIMUM_ABBREV;
> - } else if (the_hash_algo->hexsz < options->abbrev) {
> + } else if (the_hash_algo->hexsz < v) {
> options->abbrev = the_hash_algo->hexsz;
> + } else {
> + options->abbrev = v;
I've cut out a few instances of more-or-less repeated code. Any
possibility of extracting this into a helper? Maybe after you've done
the preparatory work of unifying these sites. Or as part of it, i.e.,
"let's switch this spot to use the helper; that makes it stricter in
this-and-that sense".
These can't all be entirely unified, I guess, but maybe "mostly"?
Martin
