Re: PSQL commands: \quit_if, \quit_unless

Hello Robert,

>> Your experience as an seasoned core developer and a committer is 
>> probably different:-)
>
> Well, everybody can have their own opinion on what is reasonable.

Sure.

> There are times I argue for making a patch smaller (frequent) and
> times when I argue for making it bigger (rare).

Yep.

> We had pretty much this exact same argument about the pgbench lexer and 
> parser and in the event I coded something up in less than a day.  This 
> argument feels like a rerun of that one.

There are some differences: pgbench already had one operator at a time 
expressions, while psql has survived till today with none, which suggest a 
less pressing need.

Moreover the features are partly orthogonal and would touch psql 
significantly in different although probably overlapping areas: - expressions is rather about \set, even if reused with
\ifas well - condition is about \if ... \endif and ignoring some input lines
 

The current expression evaluation in pgbench is about 1000 lines for 
scanning, parsing & evaluating, and does not yet support boolean 
expressions, although a patch for that has been in the queue for some 
time. I foresee that someone will suggest/require/demand... that the 
expression code be shared between pgbench and psql, which is another 
argument for dissociating these two features (expression and conditional 
in psql) from the start.

-- 
Fabien.