Tom Lane wrote:
> Thomas Hallgren <thomas@tada.se> writes:
>
>> What I'm proposing should be an addition that also can be seen as the
>> beginning of a path to migrate the CREATE TYPE construct to conform with
>> the SQL 2003 standard.
>>
>
> I'd be interested to see where in the SQL2003 spec the syntax you are
> proposing can be found.
>
The PostgreSQL specific semantics with input/output/receive/send is are
not in the SQL 2003 standard. But it does define how methods can be
declared on a type and to me, the input/output/receive/send are as close
to constructors and instance methods as you can get. I'm *not*
suggesting a full implementation of this. I am merely stating that
moving functions into the type and adding a column to the pg_proc table
that allows a function to be tied to a type is a step in that direction:
Here's an example using SQL 2003 syntax (from JRT-2003). The BNF is below:
CREATE TYPE addr EXTERNAL NAME 'address_classes_jar:Address' LANGUAGE JAVA AS ( street_attr CHARACTER
VARYING(50)EXTERNAL NAME 'street', zip_attr CHARACTER(10) EXTERNAL NAME 'zip' ) CONSTRUCTOR METHOD addr
() RETURNS addr SELF AS RESULT EXTERNAL NAME 'Address', CONSTRUCTOR METHOD addr (s_parm CHARACTER
VARYING(50),z_parm
CHARACTER(10)) RETURNS addr SELF AS RESULT EXTERNAL NAME 'Address', METHOD to_string () RETURNS
CHARACTERVARYING(255) EXTERNAL NAME 'toString', STATIC METHOD contiguous (A1 addr, A2 addr) RETURNS
CHARACTER(3) EXTERNAL NAME 'contiguous';
<user-defined type definition> ::= CREATE TYPE <user-defined type body>
<user-defined type body> ::= <schema-resolved user-defined type name> [ <subtype clause> ] [ AS <representation>
] [ <user-defined type option list> ] [ <method specification list> ]
...
<method specification list> ::= <method specification> [ { <comma> <method specification> }... ]
<method specification> ::= <original method specification>| <overriding method specification>
<original method specification> ::= <partial method specification> [ SELF AS RESULT ] [ SELF AS LOCATOR ] [ <method
characteristics>]
<overriding method specification> ::= OVERRIDING <partial method
specification>
<partial method specification> ::= [ INSTANCE | STATIC | CONSTRUCTOR ] METHOD <method name> <SQL parameter
declarationlist> <returns clause> [ SPECIFIC <specific method name> ]
<specific method name> ::= [ <schema name> <period> ]<qualified identifier>
<method characteristics> ::= <method characteristic>...
<method characteristic> ::= <language clause> | <parameter style clause> | <deterministic characteristic> | <SQL-data
accessindication> | <null-call clause>
Regards,
Thomas Hallgren
