Re: [PATCH v2 06/10] diff-delta: explicitly mark intentional use of the comma operator

> Hi Patrick,
> On Wed, 26 Mar 2025, Patrick Steinhardt wrote:
>> Hm. I think the end result is even more confusing than before. Why don't
>> we introduce curly braces here, same as in preceding commits?
> 
> The interleaved -/+ lines make it admittedly hard to see what I meant.
> I'll unwind it a bit (presenting only the `moff` part, the same
> consideration applies to `msize`):
> 
> 		if (moff & 0x000000ff)
> 			(void)(out[outpos++] = moff >> 0),  i |= 0x01;
> 		if (moff & 0x0000ff00)
> 			(void)(out[outpos++] = moff >> 8),  i |= 0x02;
> 		if (moff & 0x00ff0000)
> 			(void)(out[outpos++] = moff >> 16), i |= 0x04;
> 		if (moff & 0xff000000)
> 			(void)(out[outpos++] = moff >> 24), i |= 0x08;
> 
> In this form, it is very obvious (from comparing the right-side half of
> the lines) that a shifted version of `moff` is appended to `out` and `i`
> gets a bit set, and the correlation between shift width and the set bit
> is relatively easy to see and validate (at least my brain has an easy time
> here, thanks to the alignment and thanks to visual similarity between the
> non-blank parts).
> 
> It is admittedly quite a bit harder not to be distracted by the repetitive
> `(void)(out[...` parts to understand and validate the `if` conditions on
> the left-hand side,

> and being only one line between those `if` lines, I can bring my brain to
> focus only on the differences of the bitmask and understand and verify
> them with relatively little effort.
> 
> When I compared this form to the following, the cognitive load to wrap my
> head around the code is quite a bit higher there:
> 
> 		if (moff & 0x000000ff) {
> 			out[outpos++] = moff >> 0;
> 			i |= 0x01;
> 		}
> 		if (moff & 0x0000ff00) {
> 			out[outpos++] = moff >> 8;
> 			i |= 0x02;
> 		}
> 		if (moff & 0x00ff0000) {
> 			out[outpos++] = moff >> 16;
> 			i |= 0x04;
> 		}
> 		if (moff & 0xff000000) {
> 			out[outpos++] = moff >> 24;
> 			i |= 0x08;
> 		}
> 
> The reason is the visual distance between the near-identical code.
> 
> Having said that, I do realize that my brain quite possibly works in
> special ways here and that the general preference is to go with the latter
> form.
> 
> Do you have a strong opinion which form to use?
> 
> Ciao,
> Johannes
>