Re: [PATCH 1/4] sparse-checkout: extract add_patterns_from_input()

"Derrick Stolee via GitGitGadget" [off-list ref] writes:

-static int sparse_checkout_set(int argc, const char **argv, const char *prefix)
+static void add_patterns_from_input(struct pattern_list *pl,
+				    int argc, const char **argv)

Separating out what happens _after_ parse_options into its own
helper function makes sense.

Everything, not limited to this function, works on its input, so the
name suffix does not add much value to the readers.  IOW, I do not
think I, as a new reader of this code, would be confused if this
function were called add_patterns().

If we wanted to add more words to the name, perhaps I'd use them to
describe the shape of the input (e.g. "add_patterns_from_acav") but
that is obvious from the list of input parameter, so...

I haven't read the rest of the series, but will we ever call this
helper function with an array we manufacture ourselves?  If the
input array is known to be NULL terminated (and at this step in the
series, it certainly is, as we are using the ac/av supplied by the C
runtime entry point), perhaps we can omit argc from the parameter to
simplify the calling convention a bit?

 {
 	int i;
-	struct pattern_list pl;
-	int result;
-	int changed_config = 0;
-
-	static struct option builtin_sparse_checkout_set_options[] = {
-		OPT_BOOL(0, "stdin", &set_opts.use_stdin,
-			 N_("read patterns from standard in")),
-		OPT_END(),
-	};
-
-	repo_read_index(the_repository);
-	require_clean_work_tree(the_repository,
-				N_("set sparse-checkout patterns"), NULL, 1, 0);
-
-	memset(&pl, 0, sizeof(pl));
-
-	argc = parse_options(argc, argv, prefix,
-			     builtin_sparse_checkout_set_options,
-			     builtin_sparse_checkout_set_usage,
-			     PARSE_OPT_KEEP_UNKNOWN);
-
 	if (core_sparse_checkout_cone) {
 		struct strbuf line = STRBUF_INIT;
 
-		hashmap_init(&pl.recursive_hashmap, pl_hashmap_cmp, NULL, 0);
-		hashmap_init(&pl.parent_hashmap, pl_hashmap_cmp, NULL, 0);
-		pl.use_cone_patterns = 1;
+		hashmap_init(&pl->recursive_hashmap, pl_hashmap_cmp, NULL, 0);
+		hashmap_init(&pl->parent_hashmap, pl_hashmap_cmp, NULL, 0);
+		pl->use_cone_patterns = 1;
...