Re: pl/pgsql feature request: shorthand for argument and local variable references - Mailing list pgsql-hackers

why are you using yet another special syntax for this ?

would it not be better to do something like this:
CREATE FUNCTION a_reall_long_and_winding_function_name(i int, out o int)
LANGUAGE plpgsql AS $plpgsql$
DECLARE
   args function_name_alias
BEGIN
  args.o = 2 * args.i
END;
$plpgsql$;

or at least do something based on block labels (see end of
https://www.postgresql.org/docs/13/plpgsql-structure.html )

CREATE FUNCTION somefunc() RETURNS integer AS $$
<< outerblock >>
DECLARE
...

maybe extend this to

CREATE FUNCTION somefunc() RETURNS integer AS $$
<< functionlabel:args >>
<< outerblock >>
DECLARE
...

or replace 'functionlabel' with something less ugly :)

maybe <<< args >>>

Cheers
Hannu



On Wed, Mar 17, 2021 at 5:05 PM Pavel Stehule <pavel.stehule@gmail.com> wrote:
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> st 17. 3. 2021 v 9:20 odesílatel Michael Paquier <michael@paquier.xyz> napsal:
>>
>> On Wed, Mar 17, 2021 at 02:06:57PM +0800, Julien Rouhaud wrote:
>> > I also think that there should be a single usable top label, otherwise it will
>> > lead to confusing code and it can be a source of bug.
>>
>> Okay, that's fine by me.  Could it be possible to come up with an
>> approach that does not hijack the namespace list contruction and the
>> lookup logic as much as it does now?  I get it that the patch is done
>> this way because of the ordering of operations done for the initial ns
>> list creation and the grammar parsing that adds the routine label on
>> top of the root one, but I'd like to believe that there are more solid
>> ways to achieve that, like for example something that decouples the
>> root label and its alias, or something that associates an alias
>> directly with its PLpgSQL_nsitem entry?
>
>
> I am checking it now, and I don't see any easy solution. The namespace is a one direction tree - only backward iteration from leafs to roots is supported. At the moment, when I try to replace the name of root ns_item, this root ns_item is referenced by the function's arguments (NS_TYPE_VAR type). So anytime I need some  helper ns_item node, that can be a persistent target for these nodes. In this case is a memory overhead of just one ns_item.
>
> orig_label <- argument1 <- argument2
>
> The patch has to save the original orig_label because it can be referenced from argument1 or by "FOUND" variable. New graphs looks like
>
> new_label <- invalidated orig_label <- argument1 <- ...
>
> This tree has a different direction than is usual, and then replacing the root node is not simple.
>
> Second solution (significantly more simple) is an additional pointer in ns_item structure. In almost all cases this pointer will not be used. Because ns_item uses a flexible array, then union cannot be used. I implemented this in a patch marked as "alias-implementation".
>
> What do you think about it?
>
> Pavel
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>>
>> --
>> Michael