Re: Use an enum for RELKIND_*?

Hello.

At Tue, 18 Dec 2018 17:13:08 -0800, Andres Freund <andres@anarazel.de> wrote in
<20181219011308.mopzyvc73nwjzdb6@alap3.anarazel.de>
> Hi,
> 
> Right now there's no easy way to use the compiler to ensure that all
> places that need to deal with all kinds of relkinds check a new
> relkind.  I think we should make that easier by moving RELKIND_* to an
> enum, with the existing letters as the value.

I feel the same pain and I had thought of a kind of that before.

> Obviously we cannot really do that for FormData_pg_class.relkind, but
> switch() statements can easily cast that to RelationRelkind (or whatever
> we name it).
> 
> Does anybody see a reason not to do so?

I think we cannot use enums having base-type, so it will work
unless we forget the cast within switch(). However, I don't think
it is not a reason not to do so.

switch ((RelationRelkind) rel->rd_rel->relkind)
{
  ...
}

char is compatible with integer under our usage there. FWIW I
don't mind explict assignments in the enum definition since we
already do the similar thing there.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center