Re: Improve node type forward reference

Peter Eisentraut <peter(at)eisentraut(dot)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