Subject: Re: [PATCHv3 4/4] builtin/blame: highlight recently changed lines

From: Junio C Hamano <[email-masked]>
Date: Mon, 08 Jan 2018 11:56:11 -0800

Stefan Beller <[email-masked]> writes:

> +static struct color_field {
> +	timestamp_t hop;
> +	char col[COLOR_MAXLEN];
> +} *colorfield;
> +static int colorfield_nr, colorfield_alloc;
> +
> +static void parse_color_fields(const char *s)
> +{
> +	struct string_list l = STRING_LIST_INIT_DUP;
> +	struct string_list_item *item;
> +	enum { EXPECT_DATE, EXPECT_COLOR } next = EXPECT_COLOR;
> +
> +	/* Ideally this would be stripped and split at the same time? */
> +	string_list_split(&l, s, ',', -1);
> +	ALLOC_GROW(colorfield, colorfield_nr + 1, colorfield_alloc);
> +
> +	for_each_string_list_item(item, &l) {
> +		switch (next) {
> +		case EXPECT_DATE:
> +			colorfield[colorfield_nr].hop = approxidate(item->string);
> +			next = EXPECT_COLOR;
> +			colorfield_nr++;
> +			ALLOC_GROW(colorfield, colorfield_nr + 1, colorfield_alloc);
> +			break;

This should make sure cf[i].hop is monotonically increasing to avoid
end-user mistakes, I would think (what's 'hop' by the way?).

> +		case EXPECT_COLOR:
> +			if (color_parse(item->string, colorfield[colorfield_nr].col))
> +				die(_("expecting a color: %s"), item->string);

When you have a typo in one of your configuration files, say "[color
"blame"] highlightrecent = 1,week,blue,...", you'd want to see a bit
more than just "expecting a color: week" to help you diagnose and
resolve the issue.  Giving the name of the variable and the file the
wrong definition was found in would be needed, givin that this is
called from the config callback git_blame_config() below.

> +			next = EXPECT_DATE;
> +			break;
> +		}
> +	}
> +
> +	if (next == EXPECT_COLOR)
> +		die (_("must end with a color"));

Same here.

>  		OPT_BIT(0, "color-lines", &output_option, N_("color redundant metadata from previous line differently"), OUTPUT_COLOR_LINE),
>  		OPT_BIT(0, "color-fields", &output_option, N_("color redundant metadata fields from previous line differently"), OUTPUT_COLOR_FIELDS),
> +		OPT_BIT(0, "heated-lines", &output_option, N_("color lines by age"), OUTPUT_HEATED_LINES),

These options may be useful while having fun experimenting, but my
gut feeling is that these are too fine-grained for end-users to
tweak per invocation basis (which is what command line options are
for).  

But perhaps I am biased (as anybody else), as personally I find
anything beyond step 2/4 uninteresting, and not adding too many of
these options is consistent with that viewpoint ;-)

In any case, thanks for a fun read.