Re: [HACKERS] [PATCH] Generic type subscripting

> On Wed, Jan 20, 2021 at 11:37:32PM -0500, Dian M Fay wrote:
> On Wed Jan 20, 2021 at 2:08 PM EST, Dmitry Dolgov wrote:
> > > On Wed, Jan 20, 2021 at 11:34:16AM -0500, Dian M Fay wrote:
> > > > Thanks, I need to remember to not skipp doc building for testing process
> > > > even for such small changes. Hope now I didn't forget anything.
> > > >
> > > > > On Wed, Jan 20, 2021 at 09:58:43AM -0500, Dian M Fay wrote:
> > > >
> > > > > Here's a full editing pass on the documentation, with v45 and Pavel's
> > > > > doc-whitespaces-fix.patch applied. I also corrected a typo in one of the
> > > > > added hints.
> > > >
> > > > Great! I've applied almost all of it, except:
> > > >
> > > > + A <type>jsonb</type> value will accept assignments to nonexistent
> > > > subscript
> > > > + paths as long as the nonexistent elements being traversed are all
> > > > arrays.
> > > >
> > > > Maybe I've misunderstood the intention, but there is no requirement
> > > > about arrays for creating such an empty path. I've formulated it as:
> > > >
> > > > + A <type>jsonb</type> value will accept assignments to nonexistent
> > > > subscript
> > > > + paths as long as the last existing path key is an object or an array.
> > >
> > > My intention there was to highlight the difference between:
> > >
> > > * SET obj['a']['b']['c'] = '"newvalue"'
> > > * SET arr[0][0][3] = '"newvalue"'
> > >
> > > obj has to conform to {"a": {"b": {...}}} in order to receive the
> > > assignment of the nested c. If it doesn't, that's the error case we
> > > discussed earlier. But arr can be null, [], and so on, and any missing
> > > structure [[[null, null, null, "newvalue"]]] will be created.
> >
> > If arr is 'null', or any other scalar value, such subscripting will work
> > only one level deep because they represented internally as an array of
> > one element. If arr is '[]' the path will comply by definition. So it's
> > essentially the same as for objects with no particular difference. If
> > such a quirk about scalars being treated like arrays is bothering, we
> > could also bend it in this case as well (see the attached version).
>
> I missed that distinction in the original UPDATE paragraph too. Here's
> another revision based on v48.

Looks good, I've applied it, thanks.