Re: pgsql: Allow opclasses to provide tri-valued GIN consistent functions.

On 2014-03-31 10:31:00 +0300, Heikki Linnakangas wrote:
> On 03/23/2014 06:07 PM, Greg Stark wrote:
> >On Sun, Mar 23, 2014 at 1:22 PM, Heikki Linnakangas <hlinnakangas@vmware.com
> >>wrote:
> >
> >>The reason for the typedef is precisely that an enum is not guaranteed to
> >>be one byte. Tom suggested getting rid of the typedef, but it's needed to
> >>make sure it's stored as one byte.
> >>
> >>I'll go add a comment to it, explaining why it's needed.
> >
> >If we're not using the enum type perhaps it would be better to make it a
> >bunch of #defines? The main advantage of enum types is that the debugger
> >knows what values are legal and can decode them for you.
>
> Yeah, I think you're right. Changed it to use #defines, renamed the typedef
> to GinTernaryValue as that's more descriptive, and added a brief comment
> mentioning that a GinTernaryValue is compatible with a boolean.

It doesn't matter much in this case, but in general I find the reasoning
here less than convincing. For one, debuggers have a much easier time
providing the symbolic name (e.g. p WHATEVER_ENUM_VAL) than purely
defines. Also, it's perfectly possible to switch to the enum in
switch()es, and benefit from compiler warnings. Using defines prohibits
that...

Greetings,

Andres Freund

--
 Andres Freund                       http://www.2ndQuadrant.com/
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