Re: Improve node type forward reference - Mailing list pgsql-hackers

From Tender Wang
Subject Re: Improve node type forward reference
Date
Msg-id CAHewXN=9uog2G03UKL_7xec7HvAg_JdovV0U-wEcnE7FJCxUKg@mail.gmail.com
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In response to Re: Improve node type forward reference  (Peter Eisentraut <peter@eisentraut.org>)
List pgsql-hackers


Peter Eisentraut <peter@eisentraut.org> 于2024年10月15日周二 15:02写道:
On 14.10.24 23:28, Nathan Bossart wrote:
> On Mon, Oct 14, 2024 at 09:47:59AM +0200, Peter Eisentraut wrote:
>> But we can do this better by using an incomplete struct, like
>>
>>          struct Query *viewQuery ...;
>>
>> That way, everything has the correct type and fewer casts are required. This
>> technique is already used elsewhere in node type definitions.

Agree.  The attached patches LGTM.
 
>
> I noticed that the examples in parsenodes.h are for structs defined within
> the same file.  If the struct is defined in a separate file, I guess you
> might need to include another header file wherever it is used, but that
> doesn't seem too bad.

No, you can leave the struct incomplete.  You only need to provide its
full definition (= include the other header file) if you actually want
to access the struct's fields.


Yeah.   There are many examples. For example as below:
in struct RelOptInfos,

/* use "struct FdwRoutine" to avoid including fdwapi.h here */
struct FdwRoutine *fdwroutine pg_node_attr(read_write_ignore);

--
Thanks,
Tender Wang

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