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Re: Declaring a field that is also an out parameter in a function
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* Re: Declaring a field that is also an out parameter in a function
@ 2024-07-07 07:31  Pavel Stehule <[email protected]>
  0 siblings, 2 replies; 5+ messages in thread

From: Pavel Stehule @ 2024-07-07 07:31 UTC (permalink / raw)
  To: Tom Lane <[email protected]>; +Cc: Michael Nolan <[email protected]>; pgsql-general

ne 7. 7. 2024 v 0:14 odesílatel Tom Lane <[email protected]> napsal:

> Michael Nolan <[email protected]> writes:
> > Shouldn't declaring a field that is also an OUT parameter throw an error?
>
> No.  The DECLARE is a block nested within the function,
> and the parameter is declared at function scope.
> So this is a standard case of an inner declaration masking
> an outer one.
>
> Possibly plpgsql_check can be set to complain about such cases,
> but they're legal according to the language specification.
>

yes, it does

(2024-07-07 09:27:14) postgres=# select * from
plpgsql_check_function('test_function');
┌───────────────────────────────────────────────────────────────┐
│                    plpgsql_check_function                     │
╞═══════════════════════════════════════════════════════════════╡
│ warning:00000:10:statement block:parameter "d3" is overlapped │
│ Detail: Local variable overlap function parameter.            │
│ warning extra:00000:8:DECLARE:never read variable "d3"        │
│ warning extra:00000:unused parameter "$1"                     │
│ warning extra:00000:unused parameter "$2"                     │
│ warning extra:00000:unused parameter "$3"                     │
│ warning extra:00000:unmodified OUT variable "d3"              │
└───────────────────────────────────────────────────────────────┘
(7 rows)

but looks so there are false alarms related to using an alias. It is
interesting so I have not any report about this issue, so probably using
aliases is not too common today.

Regards

Pavel


>
>                         regards, tom lane
>
>
>


^ permalink  raw  reply  [nested|flat] 5+ messages in thread

* Re: Declaring a field that is also an out parameter in a function
@ 2024-07-07 09:13  Pavel Stehule <[email protected]>
  parent: Pavel Stehule <[email protected]>
  1 sibling, 1 reply; 5+ messages in thread

From: Pavel Stehule @ 2024-07-07 09:13 UTC (permalink / raw)
  To: Tom Lane <[email protected]>; +Cc: Michael Nolan <[email protected]>; pgsql-general

ne 7. 7. 2024 v 9:31 odesílatel Pavel Stehule <[email protected]>
napsal:

>
>
> ne 7. 7. 2024 v 0:14 odesílatel Tom Lane <[email protected]> napsal:
>
>> Michael Nolan <[email protected]> writes:
>> > Shouldn't declaring a field that is also an OUT parameter throw an
>> error?
>>
>> No.  The DECLARE is a block nested within the function,
>> and the parameter is declared at function scope.
>> So this is a standard case of an inner declaration masking
>> an outer one.
>>
>> Possibly plpgsql_check can be set to complain about such cases,
>> but they're legal according to the language specification.
>>
>
> yes, it does
>
> (2024-07-07 09:27:14) postgres=# select * from
> plpgsql_check_function('test_function');
> ┌───────────────────────────────────────────────────────────────┐
> │                    plpgsql_check_function                     │
> ╞═══════════════════════════════════════════════════════════════╡
> │ warning:00000:10:statement block:parameter "d3" is overlapped │
> │ Detail: Local variable overlap function parameter.            │
> │ warning extra:00000:8:DECLARE:never read variable "d3"        │
> │ warning extra:00000:unused parameter "$1"                     │
> │ warning extra:00000:unused parameter "$2"                     │
> │ warning extra:00000:unused parameter "$3"                     │
> │ warning extra:00000:unmodified OUT variable "d3"              │
> └───────────────────────────────────────────────────────────────┘
> (7 rows)
>
> but looks so there are false alarms related to using an alias. It is
> interesting so I have not any report about this issue, so probably using
> aliases is not too common today.
>

I was blind, plpgsql_check is correct

Regards

Pavel


>
> Regards
>
> Pavel
>
>
>>
>>                         regards, tom lane
>>
>>
>>


^ permalink  raw  reply  [nested|flat] 5+ messages in thread

* Re: Declaring a field that is also an out parameter in a function
@ 2024-07-07 13:01  Michael Nolan <[email protected]>
  parent: Pavel Stehule <[email protected]>
  0 siblings, 1 reply; 5+ messages in thread

From: Michael Nolan @ 2024-07-07 13:01 UTC (permalink / raw)
  To: Pavel Stehule <[email protected]>; +Cc: Tom Lane <[email protected]>; pgsql-general

On Sun, Jul 7, 2024 at 4:13 AM Pavel Stehule <[email protected]> wrote:
>
> but looks so there are false alarms related to using an alias. It is interesting so I have not any report about this issue, so probably using aliases is not too common today.

I'm not sure why there's a warning about using an alias. 43.3.1 says
to use them for improved readability.

Mike Nolan






^ permalink  raw  reply  [nested|flat] 5+ messages in thread

* Re: Declaring a field that is also an out parameter in a function
@ 2024-07-07 14:37  Tom Lane <[email protected]>
  parent: Pavel Stehule <[email protected]>
  1 sibling, 0 replies; 5+ messages in thread

From: Tom Lane @ 2024-07-07 14:37 UTC (permalink / raw)
  To: Pavel Stehule <[email protected]>; +Cc: Michael Nolan <[email protected]>; pgsql-general

Pavel Stehule <[email protected]> writes:
> (2024-07-07 09:27:14) postgres=# select * from
> plpgsql_check_function('test_function');
> ┌───────────────────────────────────────────────────────────────┐
> │                    plpgsql_check_function                     │
> ╞═══════════════════════════════════════════════════════════════╡
> │ warning:00000:10:statement block:parameter "d3" is overlapped │
> │ Detail: Local variable overlap function parameter.            │

Nice!  FWIW, I think the standard terminology is "local variable
shadows function parameter".

			regards, tom lane






^ permalink  raw  reply  [nested|flat] 5+ messages in thread

* Re: Declaring a field that is also an out parameter in a function
@ 2024-07-07 14:42  Pavel Stehule <[email protected]>
  parent: Michael Nolan <[email protected]>
  0 siblings, 0 replies; 5+ messages in thread

From: Pavel Stehule @ 2024-07-07 14:42 UTC (permalink / raw)
  To: Michael Nolan <[email protected]>; +Cc: Tom Lane <[email protected]>; pgsql-general

ne 7. 7. 2024 v 15:01 odesílatel Michael Nolan <[email protected]> napsal:

> On Sun, Jul 7, 2024 at 4:13 AM Pavel Stehule <[email protected]>
> wrote:
> >
> > but looks so there are false alarms related to using an alias. It is
> interesting so I have not any report about this issue, so probably using
> aliases is not too common today.
>
> I'm not sure why there's a warning about using an alias. 43.3.1 says
> to use them for improved readability.
>

it is obsolete - aliases were used when Postgres doesn't support named
arguments.

I  don't know any good reason why one variable can use more than one name.

There can be an exception when argument names are very long, but generally
they are not used.



>
> Mike Nolan
>


^ permalink  raw  reply  [nested|flat] 5+ messages in thread


end of thread, other threads:[~2024-07-07 14:42 UTC | newest]

Thread overview: 5+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2024-07-07 07:31 Re: Declaring a field that is also an out parameter in a function Pavel Stehule <[email protected]>
2024-07-07 09:13 ` Pavel Stehule <[email protected]>
2024-07-07 13:01   ` Michael Nolan <[email protected]>
2024-07-07 14:42     ` Pavel Stehule <[email protected]>
2024-07-07 14:37 ` Tom Lane <[email protected]>

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