Re: [HACKERS] [PATCH] Generic type subscripting

> On 14 November 2017 at 22:25, Dmitry Dolgov <9erthalion6@gmail.com> wrote:

> But now I wonder if `resnull` is really needed in `jsonb_get_element`,

> `array_get_element` and it seems to me that I can even get rid of it so

On the second thought, no, looks like I'm wrong and it should be like this. The

reason is that any `fetch` function should be in form

    (container, internal) -> extracted value

which means that we need to return an extracted value (for jsonb it's a `jsonb`,

for array it's an `anyelement`). But at the same time in general case we can

figure out if the result is null only inside a `fetch` function,

(`jsonb_get_element` for jsonb or whatever it may be for a custom data type)

because it returns Datum. So the only way to return this information is by

reference through the `internal` argument. To summarize, If as you said it's

not that critical, I would suggest to leave it as it is.