Re: [HACKERS] plpgsql doesn't coerce boolean expressions to boolean - Mailing list pgsql-sql

From Tom Lane
Subject Re: [HACKERS] plpgsql doesn't coerce boolean expressions to boolean
Date
Msg-id 3559.1063128729@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] plpgsql doesn't coerce boolean expressions to boolean  (Jan Wieck <JanWieck@Yahoo.com>)
Responses Re: [HACKERS] plpgsql doesn't coerce boolean expressions to boolean  (Jan Wieck <JanWieck@Yahoo.com>)
List pgsql-sql
Jan Wieck <JanWieck@Yahoo.com> writes:
> ERROR is the cleanest way, but I'd vote for conversion to boolean to 
> keep the damage within reason.

Which style of conversion did you like?  These were the choices:

>> 3. Try to convert nonbooleans to boolean using plpgsql's usual method
>> for cross-type coercion, ie run the type's output proc to get a
>> string and feed it to bool's input proc.  (This seems unlikely to
>> avoid throwing an error in very many cases, but it'd be the most
>> consistent with other parts of plpgsql.)
>> 
>> 4. Use the parser's coerce_to_boolean procedure, so that nonbooleans
>> will be accepted in exactly the same cases where they'd be accepted
>> in a boolean-requiring SQL construct (such as CASE).  (By default,
>> none are, so this isn't really different from #2.  But people could
>> create casts to boolean to override this behavior in a controlled
>> fashion.)

At this point I'm kinda leaning to #4, because (for example) people
could create a cast from integer to boolean to avoid having to fix their
plpgsql functions right away.  #3 would not offer any configurability of
behavior.
        regards, tom lane


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