RE: [HACKERS] Associative Operators? (Was: Re: [NOVICE] Out of f rying pan, into fire)

However it is implemented, I would really enjoy this enhancement.
Additionally, it would be nice if I could create a new operator using C and
have this new operator be associative if desired.

Speaking of this, If either LASTNAME or FIRSTNAME is NULL then the result of
((LASTNAME || ',' ) || FIRSTNAME) will return NULL.  I would like to be able
to alter this such that the result will contain what ever is not NULL.  I
tried to create a C function to overcome this but noticed that if any
parameter in my C function is NULL then the C function always returns NULL.
I saw some references in the archives about this issue but was unable to
determine where it was left.  What is the status of this issue?

Thanks, Michael
-----Original Message-----From:    Bruce Momjian [SMTP:maillist@candle.pha.pa.us]Sent:    Tuesday, March 16, 1999 3:24
PMTo:   clark.evans@manhattanproject.comCc:    hackers@postgreSQL.orgSubject:    Re: [HACKERS] Associative Operators?
(Was:Re:
 
[NOVICE] Out of frying pan, into fire)
> Seth McQuale pointed out that the follwing does not work:>   SELECT LASTNAME || ',' || FIRSTNAME [AS] NAME FROM
FRIENDS;>> The solution, was:>   SELECT ( LASTNAME || ',' ) || FIRSTNAME AS NAME FROM FRIENDS;> > I looked at
pg_operatorand didn't see any flag to mark> an operator as 'associative'.   Perhaps if we added a flag> like this, the
re-writesystem could be modified to handle> cases like this.> > Thoughts?> > Clark Evans> > 
 
My guess is that we should auto-left-associate functions like || if
noparens are present.  It would be a small change to the parser.
--   Bruce Momjian                        |  http://www.op.net/~candle  maillist@candle.pha.pa.us            |  (610)
853-3000 +  If your life is a hard drive,     |  830 Blythe Avenue  +  Christ can be your backup.        |  Drexel
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