Reserved words and named function parameters

Tom Lane wrote:

I've been reviewing Dennis Bjorklund's patch to support named
function parameters:
http://archives.postgresql.org/pgsql-patches/2003-12/msg00176.php

One thing I didn't like about it was that the grammar declared
param_name as plain IDENT, meaning that you could not use even
"unreserved" keywords as param names. One would prefer ColId, but
naturally that causes a truckload of shift and reduce conflicts :-(

After some fooling around I find that these combinations work:

1. Make param_name equate to type_name (allowing IDENT or
unreserved_keyword), and move the following keywords from
"unreserved" to "col_name_keyword" status:
DOUBLE INOUT NATIONAL OUT

2. Make param_name equate to function_name (allowing IDENT,
unreserved_keyword, or func_name_keyword). This requires the
above changes plus moving "IN" from func_name_keyword to fully
reserved status.

Any opinions which to do, or alternate proposals? I'm leaning
slightly to #2, since I doubt anyone is trying to use "IN" as
a function name, but ...

I support #2 rather more strongly ;-)

cheers

andrew

Andrew Dunstan <andrew@dunslane.net> writes:

Tom Lane wrote:

1. Make param_name equate to type_name (allowing IDENT or
unreserved_keyword), and move the following keywords from
"unreserved" to "col_name_keyword" status:
DOUBLE INOUT NATIONAL OUT

2. Make param_name equate to function_name (allowing IDENT,
unreserved_keyword, or func_name_keyword). This requires the
above changes plus moving "IN" from func_name_keyword to fully
reserved status.

Any opinions which to do, or alternate proposals? I'm leaning
slightly to #2, since I doubt anyone is trying to use "IN" as
a function name, but ...

I support #2 rather more strongly ;-)

After further fooling about, I think it might be better to transfer
PRECISION instead of DOUBLE to the col_name_keyword category. The
reason we need to do one or the other is
create function foo(double precision) ...
If both words are unreserved then there are two possible parses ---
either "double precision" as a type spec, or "double" as a parameter
name and "precision" as a type name.

The reason for not wanting to make "double" even a little bit reserved
is that this regression test fails with a syntax error:

CREATE TYPE widget (
internallength = 24,
input = widget_in,
output = widget_out,
alignment = double
);

We could require people to start quoting "double" in this context, but
I think the path of least resistance is probably to make "precision"
a little bit reserved, instead. Anyone have a strong attachment to
custom datatypes named either?

regards, tom lane

Any opinions which to do, or alternate proposals? I'm leaning
slightly to #2, since I doubt anyone is trying to use "IN" as
a function name, but ...

One addition. The information_schema.parameters view will need to be
updated to reflect parameter names.

http://www.postgresql.org/docs/7.4/static/infoschema-parameters.html

Quote: "Always null, since PostgreSQL does not support named parameters"

Chris