Hi Pavel,
I guess this represents most exactly what this professor is thinking
about -- being able to create methods and types with methods which can
be nested -- but syntactical details are of secondary importance.
All the best, Nick
On 02/01/2011 05:43 AM, Pavel Stehule wrote:
Hello
it is part of ANSi SQL 2003
http://savage.net.au/SQL/sql-2003-2.bnf.html#method%20specification%20designator
2011/2/1 Pavel Stehule<pavel.steh...@gmail.com>:
2011/2/1 Robert Haas<robertmh...@gmail.com>:
On Mon, Jan 31, 2011 at 5:09 PM, Nick Rudnick<joerg.rudn...@t-online.de> wrote:
Interesting... I remember that some years ago, I fiddled around with
functions, operators etc. to allow a method like syntax -- but I ever was
worried this approach would have serious weaknesses -- are there any
principal hindrances to having methods, if no, can this be implemented in a
straightforward way?
It would help if you were a bit more specific. Do you mean you want
to write something like foo.bar(baz) and have that mean call the bar
method of foo and pass it baz as an argument?
If so, that'd certainly be possible to implement for purposes of a
college course, if you're so inclined - after all it's free software -
but we'd probably not make such a change to core PG, because right now
that would mean call the function bar in schema baz and pass it foo as
an argument. We try not to break people's code to when adding
nonstandard features.
I has not a standard, so I am not sure what is in standard and what
not. It was a popular theme about year 2000 and OOP was planed to
SQL3. You can find a some presentation from this time. Oracle
implemented these features.
J. Melton: SQL:1999: Understanding Object-Relational and
Other Advanced Features, Morgan Kaufmann, 2003.
CREATE METHOD next_color (n INT)
RETURNS INT
FOR colored_part_t
RETURN SELF.color_id + n
SELECT partno, color_id, DEREF(oid).next_color(1) AS next
FROM colored_parts
some other databases implemented a dereferenced data (it's not only
Oracle's subject)
http://www.java2s.com/Code/Oracle/Object-Oriented-Database/DEREFDereferencetheRowAddresses.htm
Probably DB2 implements this functionality too. See doc for CREATE
TYPE statement, REF USING, NOT FINAL, method specification
CREATE TYPE type-name
...
METHOD attribute-name()
RETURNS attribute-type
these features are very nice - but is not well documented and probably not used.
Pavel
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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