Jeff King <peff@xxxxxxxx> writes:
> On Thu, Nov 20, 2014 at 11:44:26AM -0800, Junio C Hamano wrote:
>
>> > @@ -32,10 +32,13 @@ struct color {
>> > COLOR_UNSPECIFIED = 0,
>> > COLOR_NORMAL,
>> > COLOR_ANSI, /* basic 0-7 ANSI colors */
>> > - COLOR_256
>> > + COLOR_256,
>> > + COLOR_RGB
>> > } state;
>> > /* The numeric value for ANSI and 256-color modes */
>> > unsigned char value;
>> > + /* 24-bit RGB color values */
>> > + unsigned char red, green, blue;
>>
>> Do value and rgb have to be both valid at the same time, or is this
>> "we are not wasting a byte by not using a union because it will be
>> in the padding of the outer struct anyway"?
>
> The latter. I started with a union, and then realized that COLOR_ANSI
> and COLOR_256 shared the value, so the union was not saving space and
> just getting in the way (mostly because I had to think of useful names
> for each of the members).
>
> I'd be happy to do it as a union if you think that makes it clearer.
>
> Also, the name "state" should perhaps be "type". It originally
> started as "unspecified or an actual value", which is a state, but
> as I worked, it grew into something more.
I think use of union might be more "kosher", e.g.
struct color_spec {
enum { ... } type;
union {
struct { unsigned char r, g, b; } rgb;
unsigned char ansi;
} u;
} c;
but it is not like you have an array of these things for each slot,
and with the intervening ".u.<type>" you have to write every time
you refer to these fields, the result is probably much uglier and
harder to read. So let's only do s/state/type/ and leave these
"ought to be union but that will be uglier" ones as they are.
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