polymorphic parameters limits - correct solution? - Mailing list pgsql-hackers

From Pavel Stehule
Subject polymorphic parameters limits - correct solution?
Date
Msg-id CAFj8pRDxOrWvS2+L0bE8=S1BKgre0eDRxtTc9zBk7XmAZgEBnA@mail.gmail.com
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Responses Re: polymorphic parameters limits - correct solution?
List pgsql-hackers
Hi

I played with introduction of new pair of Polymorphic Parameters - like anyXelement and anyXarray. Now, I don't think so enhancing PP is good way now. Without significant redesign there are not practical append more code there.

Why this is a issue? The extension's authors are not able to specify result type without enumeration of all possible function signatures. Similar situation is in argument processing - there are workaround based on "any" type.

Can we design helper function used only for function that returns "any"  type, that returns correct result type?

some like

CREATE OR REPLACE FUNCTION fx("any", "any")
RETURNS "any" AS ...

CREATE OR REPLACE FUNCTION fx_helper(Oid[])
RETURNS Oid AS ..

ALTER FUNCTION fx("any", "any") SET ('result_helper', 'fx_helper'::regproc);

possibly, there can be some argument helper, that can specify UNKNOWN arguments.

Notes, comments?

Regards

Pavel

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