Re: [PATCH 2/2] bisect: rewrite `check_term_format` shell function in C
On Wed, May 4, 2016 at 1:07 AM, Pranit Bauva <pranit.bauva@gmail.com> wrote:
> This reimplements the `check_term_format` shell function in C and adds
s/This reimplements/Reimplement/ s/adds/add/
> a `--check-term-format` subcommand to `git bisect--helper` to call it
> from git-bisect.sh
s/$/./
Okay, I'll bite: Why is this a good idea? What does it buy you?
It's not as if the rewrite is especially faster or more easily expressed in C; quite the contrary, the shell code is more concise and probably about equally as fast (not that execution speed matters in this case).
I could understand this functionality being ported to C in the form of a static function as a minor part of porting "git bisect terms" in its entirety to C, but I'm not imaginative enough to see why this functionality is useful as a standalone git-bisect--helper subcommand, and the commit message doesn't enlighten. Consequently, it seems like unnecessary complexity.
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> Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
> ---
> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
> @@ -2,16 +2,66 @@
> static const char * const git_bisect_helper_usage[] = {
> N_("git bisect--helper --next-all [--no-checkout]"),
> + N_("git bisect--helper --check-term-format <term> <orig_term>"),Could this be shortened to --check-term or would that be undesirable?
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> NULL
> };
>
> enum sub_commands {
> - NEXT_ALL = 1
> + NEXT_ALL = 1,
> + CHECK_TERM_FMT
> };
>
> +/*
> + * To check whether the string `term` belongs to the set of strings
> + * included in the variable arguments so as to make the code look
> + * clean and avoid having long lines in the `if` statement.
> + */Is this a (long) sentence fragment? Code cleanliness is an obviously desirable trait, thus talking about it in the comment adds no value; it's just noise.
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> +static int one_of(const char *term, ...)
> +{
> + va_list matches;
> + const char *match;
> +
> + va_start(matches, term);
> + while ((match = va_arg(matches, const char *)) != NULL)
> + if (!strcmp(term, match))
> + return 1;Is it wise to return here without invoking va_end()?
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> + va_end(matches);
> +
> + return 0;
> +}
> +
> +static int check_term_format(const char *term, const char *orig_term,
> + int flag)
What is 'flag' for? The single caller only ever passes 0, so why is this needed?
> +{
> + struct strbuf new_term = STRBUF_INIT;'new_term' is being leaked at every 'return' statement in this function.
> + strbuf_addf(&new_term, "refs/bisect/%s", term);
> +
> + if (check_refname_format(new_term.buf, flag))
> + die(_("'%s' is not a valid term\n"), term);Why does this die() while the other "invalid" cases merely return error()? What makes this special?
Also, drop "\n" from the error string.
> + else if (one_of(term, "help", "start", "skip", "next", "reset",
> + "visualize", "replay", "log", "run", NULL))
> + return error("can't use the builtin command '%s' as a term\n", term);This should be wrapped in _(...). Also, drop the "\n".
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> + /*
> + * In theory, nothing prevents swapping
> + * completely good and bad, but this situation
> + * could be confusing and hasn't been tested
> + * enough. Forbid it for now.
> + */
This would be a bit easier to read if re-wrapped to fit within 80 columns rather than 53 or so.
> + else if ((one_of(term, "bad", "new", NULL) && strcmp(orig_term, "bad")) ||
> + (one_of(term, "good", "old", NULL) && strcmp(orig_term, "good")))
This can be more efficient by doing the strcmp() before the expensive one_of():
if ((strcmp(...) && one_of(...)) ||
strcmp(...) && one_of(...)))> + return error("can't change the meaning of the term '%s'\n", term);This should be wrapped in _(...). Also, drop the "\n".
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> + return 0;
> +}
> +
> int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
> {
> int sub_command = 0;
> @@ -19,6 +69,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
> struct option options[] = {
> OPT_CMDMODE(0, "next-all", &sub_command,
> N_("perform 'git bisect next'"), NEXT_ALL),
> + OPT_CMDMODE(0, "check-term-format", &sub_command,
> + N_("check format of the ref"), CHECK_TERM_FMT),Show 10 quoted lines
> OPT_BOOL(0, "no-checkout", &no_checkout,
> N_("update BISECT_HEAD instead of checking out the current commit")),
> OPT_END()
> @@ -33,6 +85,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
> switch (sub_command) {
> case NEXT_ALL:
> return bisect_next_all(prefix, no_checkout);
> + case CHECK_TERM_FMT:
> + if (argc != 2)
> + die(_("--check-term-format should be followed by exactly 2 arguments."));Drop the period. Possible reword:
--check-term-format requires two arguments
> + return check_term_format(argv[0], argv[1], 0);
> default:
> die(_("bug: unknown subcommand '%d'"), sub_command);
> }
Pranit Bauva
