From: Tom Lane <tgl@sss.pgh.pa.us>
To: Marthin Laubscher <postgres@lobeshare.co.za>
cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Custom type's modifiers
In-reply-to: <9964489E-E1FF-4E16-89D5-6804DD7C2A4B@lobeshare.co.za>
References: <9964489E-E1FF-4E16-89D5-6804DD7C2A4B@lobeshare.co.za>
Comments: In-reply-to Marthin Laubscher <postgres@lobeshare.co.za>
	message dated "Thu, 27 Jun 2024 16:33:34 +0200"
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Date: Thu, 27 Jun 2024 11:06:27 -0400
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Marthin Laubscher <postgres@lobeshare.co.za> writes:
> But now I need to (re)define MyType to support type modifiers (e.g. MyTy=
pe(1,14,18)) and I got that done using CREATE TYPE=E2=80=99s TYPMOD_IN and=
 TYPMOD_OUT parameters resulting in the correct packed value getting store=
d in pg_attribute when I define a column of that type. =


OK ...

> But when I pass a MyType value to a function defined in my C extension h=
ow would I access the type modifier value for the argument which could hav=
e been drawn from the catalog or the result of a cast. =


You can't.  Whatever info is needed by operations on the type had
better be embedded in the value.

			regards, tom lane