Re: get_cast_func syscache utility function

On 11/05/2014 10:10 AM, Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>> On 11/04/2014 01:45 PM, Tom Lane wrote:
>>> In short, I'd rather see this addressed through functions with slightly
>>> higher-level APIs that are capable of covering more cases.  In most cases
>>> it'd be best if callers were using find_coercion_pathway() rather than
>>> taking shortcuts.
>> Well, then, do we really need a wrapper at all? Should we just be doing
>> something like this?
>>                   if (typoid >= FirstNormalObjectId)
>>                   {
>>                       Oid castfunc;
>>                       CoercionPathType ctype;
>>                       ctype = find_coercion_pathway(JSONOID, typoid,
>>                                                     COERCION_EXPLICIT, &castfunc);
>>                       if (ctype == COERCION_PATH_FUNC && OidIsValid(castfunc))
>>                       {
>>                           *tcategory = JSONTYPE_CAST;
>>                           *outfuncoid = castfunc;
>>                       }
>>                   }
> Well, of course, the question that immediately raises is why isn't this
> code handling the other possible CoercionPathTypes ;-).  But at least
> it's pretty obvious from the code that you are ignoring such cases,
> so yes I think this is better than what's there now.
>
>             
Also, it's equivalent to what's there now, I think. I wasn't intending 
to change the behaviour - if someone wants to do that they can submit a 
separate patch.


cheers

andrew