Re: WIP: hooking parser

Peter Eisentraut wrote:
> Tom Lane wrote:
>> Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
>>> I think what you want here is some way to define a function that
>>> takes an arbitrary number of arguments of arbitrary type and let the
>>> function figure everything out. I see no reason why this can't be a
>>> variant on CREATE FUNCTION, except that of course you need to figure
>>> out some API and function resolution details.
>>
>> We've already got "variadic any" functions --- the problem is to tell
>> the parser what the function's result type will be, given a particular
>> parameter list. I agree that hooking transformExpr is not exactly the
>> most ideal way to attack that from a performance or complexity
>> standpoint.
>
> What is the defined return type logic for the decode() function anyway?
> If you want the full CASE-like resolution logic, it might be very hard
> to fit that into a general system.

And on top of that, decode() is supposed to do short-circuit evaluation
of the arguments.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com