Re: Fixing contrib/isn for float8-pass-by-value

I was going to say something like that but couldn't come up with a  
nice syntax. The syntax you gave seems obvious in retrospect.

I wonder if this should be tied in some way with creating binary- 
compatible casts or anything. Probably not since the data type can  
just make them itself.

greg

On 28 Nov 2008, at 08:02 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

> I wrote:
>> The problem reported by Rushabh Lathia boils down to the fact that
>> contrib/isn intends to define a datatype that is represented "just  
>> like
>> int8", but it supposes that int8 must be pass by reference.  There is
>> not anything wrong with the C code; the problem is the CREATE TYPE
>> command in isn.sql.  To fix this we need some way of passing the  
>> state
>> of FLOAT8PASSBYVAL into that SQL script.
>> ...
>> This is kinda ugly but I don't really see anything better.
>
> I had a better but more invasive idea: invent a new attribute for
> CREATE TYPE
>
>    LIKE   =  typename
>
> which means "copy any unspecified representational details from the
> given pre-existing type".  This would allow the .sql file to know
> less instead of more about what's happening, so it seems more
> future-proof.  It's a bit more work than the makefile hack I was
> thinking about, but seems like a good investment.  (I wouldn't
> propose this if I thought contrib/isn was the only user --- I expect
> there are other third-party modules with similar needs.)
>
> Comments?
>
>            regards, tom lane
>
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