Re: Simplify the way of appending comma to stringInfo

On 08/12/2025 10:37, Chao Li wrote:
> Hi Hackers,
>
> In a lot places, there are logic of appending comma separators in a
> pattern like:
>
> ```
> for (int i = 0; i < len; i ++)
> {
>     if (i > 0)
>        appendStringInfoString(", ");
>     appendStringInfo(some-item);
> }
>
> ```
> This pattern uses an "if" check and two appendStringInfoString() to
> build a comma-delimited string.
>
> This can be simplified as:
>
> ```
> const char *sep = "";
> for (int i = 0; i < len; i ++)
> {
>      appendStringInfo("%s%s", sep, some-item);
>      sep = ", ";
> }
> ```
> The new pattern avoids the "if" check, and combines two
> appendStringInfoString() into a single appendStringInfo(). I think the
> new pattern is neater and faster.
>
> The old patterns are used in a lot of places, and there are some usages
> of the new pattern as well. Instead of creating a big cleanup patch, I
> just applied the new pattern to a single file for now to see if the
> hacker group likes this change.

It's a matter of taste, but I personally prefer the "old" pattern with
an explicit if() statement more. And I don't think it's worth the code
churn to change existing code either way.

- Heikki